Refactor output (err) functions.

+ Move to standard PP indents (incrementally).
+ better indenting of preprocessor directives in jam.h
+ print_source_line, backtrace_line, backtrace, and unknown_rule_error (formerly unknown_rule) function definitions moved from builtins.cpp to outerr.cpp
+ new rule_and_args_to_string and out_warning functions added
+ COMMAND builtin rule is now an alias for SHELL, to reflect the documentation and also because it is not used and one day might be discontinued
+ new function try_bind_module added to builtins.cpp, to check for modules before the binding and error/warning diagnostics; currently used by both IMPORT and EXPORT builtin rules [1]
+ new template function b2::find_hash added to simplify usage of hash_find, this is in builtins.cpp by now
+ use of "global module" instead of "root module" in messages
+ builtin_import (IMPORT) and builtin_native_rule (NATIVE_RULE) updated to use outerr functions to emit errors
+ call_member_rule in compile.cpp updated to emit a warning using out_warning
+ struct _stack::check::operator() and function_call_rule in function.cpp now emit a warning using out_warning
+ function_call_rule e function_call_member_rule in function.cpp now emit an error using out_error
+ restored "root module" in place of "global module" in messages and documentation, where appropriate
+ error issued by RULENAMES too on missing module,
+ get rid of add_rule_name function in builtins.cpp, duplicate of module_rules in modules.cpp.

[1] Requesting an import from a non-existent module produces a warning and the use of the global module by IMPORT; conversely requesting an export from a non-existent module produces an error by the EXPORT. See #565 for details about the rationale.

fixes #581

Author: paolopas

.clang-format

@@ -75,7 +75,7 @@ PenaltyBreakFirstLessLess: 0
 PenaltyReturnTypeOnItsOwnLine: 999999
 PenaltyIndentedWhitespace: 999999
 PointerAlignment: Middle
-PPIndentWidth: 0
+PPIndentWidth: 4
 ReflowComments: true
 ShortNamespaceLines: 0
 SortIncludes: CaseInsensitive

doc/src/history.adoc

@@ -3,10 +3,14 @@
 
 == Version 5.5.0
 
-* *New*: Argument lists description provided for all built-in rules,
+* *New*: Argument lists description provided for all builtin rules,
   GLOB-RECURSIVELY has become an alias of GLOB_RECURSIVELY.
+  -- _Paolo Pastori_
 * *New*: Added test for regular expressions with MATCH builtin rule.
   -- _Paolo Pastori_
+* *New*: Improved control of source module by IMPORT, EXPORT, and
+  RULENAMES builtin rules.
+  -- _Paolo Pastori_
 * *New*: Add reading/parsing of property database from JSON data to base CPS
   support from.
   -- _René Ferdinand Rivera Morell_