♻️ Set Config[:default] as alias of Config[VERSION]

The docs already claimed that `:default` was an alias for `:current`.
But, although they were equal to each other, they were not the same
object.  Now they are one and the same.

This also fixes a minor inconsistency in `Config#inspect`, because
`Config[:default].named_default?` (incorrectly) returned `false`.

Author: nevans

lib/net/imap/config.rb

@@ -578,7 +578,6 @@ def name
         if    equal? Config.default   then "#{Config}.default"
         elsif equal? Config.global    then "#{Config}.global"
         elsif equal? Config[0.0r]     then "#{Config}[:original]"
-        elsif equal? Config[:default] then "#{Config}[:default]"
         elsif (v = AttrVersionDefaults::VERSIONS.find { equal? Config[_1] })
           "%s[%0.1f]" % [Config, v]
         else

lib/net/imap/config/attr_version_defaults.rb

@@ -59,10 +59,6 @@ def self.compile_default!
         end
 
         def self.compile_version_defaults!
-          # Temporarily assign Config.default, enabling #load_defaults(:default)
-          version_defaults[:default] = Config.default
-          # Use #load_defaults so some attributes are inherited from global.
-          version_defaults[:default] = Config.new.load_defaults(:default).freeze
           version_defaults[0.0r]     = Config[version_defaults.fetch(0.0r)]
 
           VERSIONS.each_cons(2) do |prior, version|
@@ -81,6 +77,7 @@ def self.compile_version_defaults!
 
           version_defaults[:original] = Config[0.0r]
           version_defaults[:current]  = Config[CURRENT_VERSION]
+          version_defaults[:default]  = Config[CURRENT_VERSION]
           version_defaults[:next]     = Config[NEXT_VERSION]
           version_defaults[:future]   = Config[FUTURE_VERSION]