Make the default development branch configurable

Up to now, the `master` branch was the default development branch. And
now it's possible to configure it by running the `acquire-repository`
command. So, after the configuration, the provided value will be used
instead of the `master`. However, the `master` is still a default one.
But now, it's possible to set another branch as a default one (for
instance, `develop`) and Elegant Git will use it.

Author: extsoft

docs/configuration.md

@@ -34,6 +34,7 @@ if you `acquire-repository`, it proposes defaults that are set by `acquire-git`.
 2. setting your email usign `user.email` [`b`]
 3. setting a default editor using `core.editor` [`b`]
 4. setting protected branches using `elegant-git.protected-branches` [`l`]
+5. setting a default development branch using `elegant-git.default-branch` [`l`]
 
 # Level: Standards
 
@@ -84,9 +85,14 @@ For now, only `gpg` is supported. If you need other tools, please [create a new
 The Elegant Git configuration keys:
 
 - `elegant-git.protected-branches` defines the protected branches (if there are multiple values, they
-should be separarated with space). By default, `master` branch treats as protected. The "protected"
+should be separarated with space). By default, the `master` branch treats as protected. The "protected"
 means that Elegant Git commands for a branch state modification (such as `save-work`, `polish-work`,
 etc.) are prohibited to work if the current branch is protected. Also, the protected branches cannot
 be removed while running Elegant Git commands for serving a repository.
 - `elegant-git.acquired` defines whether a user was applied global configuration or not (see
 [approach](#approach) for the details).
+- `elegant-git.default-branch` defines the name of the default development branch. By default, the `master`
+branch treats as the default one. Depending on an Elegant Git command, it can be a source branch to create
+a new branch from, a destination branch to rebase work in, a base branch to compare with, a release branch,
+and can be used in other ways. In other words, the default development branch is "a golden source" of
+modifications (commits) for any manipulation that needs them.

libexec/git-elegant

@@ -28,10 +28,6 @@ git-verbose-op() {
     ${processor} "$(git "$@" 2>&1)"
 }
 
-DEFAULT_BRANCH="master"
-DEFAULT_UPSTREAM_REPOSITORY="origin"
-DEFAULT_REMOTE_TRACKING_BRANCH="${DEFAULT_UPSTREAM_REPOSITORY}/${DEFAULT_BRANCH}"
-
 _error-if-empty() {
     # _error-if-empty <a value to check> <error message>
     if [[ -z "$1" ]]; then

libexec/git-elegant-accept-work

@@ -60,6 +60,7 @@ MESSAGE
     local work_branch="__eg"
     local changes=${1}
     source ${BINS}/plugins/state
+    source ${BINS}/plugins/configuration-default-branches
     if is-there-active-rebase; then
         local rb=$(rebasing-branch)
         if [[ ${work_branch} == ${rb} ]]; then

libexec/git-elegant-acquire-repository

@@ -32,12 +32,14 @@ MESSAGE
 default() {
     source ${BINS}/plugins/configuration
     source ${BINS}/plugins/configuration-protected-branches
+    source ${BINS}/plugins/configuration-default-branches
     source ${BINS}/plugins/configuration-acquired
     obsolete-configurations-removing --local
     basics-configuration --local \
             user_name \
             user_email \
             core_editor \
+            default_branch \
             protected_branches
     if ! is-git-acquired ; then
         standards-configuration --local \

libexec/git-elegant-deliver-work

@@ -58,6 +58,7 @@ MESSAGE
 --deliver-work-logic() {
     source ${BINS}/plugins/state
     source ${BINS}/plugins/transformation
+    source ${BINS}/plugins/configuration-default-branches
     if is-there-active-rebase; then
         git-verbose rebase --continue
     else

libexec/git-elegant-polish-work

@@ -39,6 +39,7 @@ MESSAGE
 default() {
     local current_branch=$(git rev-parse --abbrev-ref HEAD)
     source ${BINS}/plugins/configuration-protected-branches
+    source ${BINS}/plugins/configuration-default-branches
     if is-branch-protected ${current_branch}; then
         error-box "The protected '${current_branch}' branch history can't be rewritten."
         error-text "Please read more on ${__site}."

libexec/git-elegant-prune-repository

@@ -43,6 +43,7 @@ MESSAGE
 
 default() {
     source ${BINS}/plugins/state
+    source ${BINS}/plugins/configuration-default-branches
     git-verbose checkout ${DEFAULT_BRANCH}
     if is-there-upstream-for ${DEFAULT_BRANCH}; then
         git-verbose fetch --all || info-text "As the remotes can't be fetched, the current local version is used."

libexec/git-elegant-release-work

@@ -59,6 +59,7 @@ MESSAGE
 }
 
 --release-work() {
+    source ${BINS}/plugins/configuration-default-branches
     git-verbose checkout ${DEFAULT_BRANCH}
     git-verbose pull --tags
     source ${BINS}/plugins/state

libexec/git-elegant-show-work

@@ -22,14 +22,15 @@ modifications, and available stashes.
 Approximate commands flow is
 \`\`\`bash
 ==>> git elegant show-work
-git log --oneline ${DEFAULT_BRANCH}..@
+git log --oneline master..@
 git status --short
 git stash list
 \`\`\`
 MESSAGE
 }
 
 default(){
+    source ${BINS}/plugins/configuration-default-branches
     local branch=$(git rev-parse --abbrev-ref @)
     info-text ">>> Branch refs:"
     info-text "local:  ${branch}"

libexec/git-elegant-start-work

@@ -43,6 +43,7 @@ MESSAGE
 
 --start-work-logic(){
     source ${BINS}/plugins/state
+    source ${BINS}/plugins/configuration-default-branches
     local target=${2:-${DEFAULT_BRANCH}}
     git-verbose checkout ${target}
     if is-there-upstream-for ${target}; then