Add right margin guideline to commit message editor

Add a right margin to the commit message editor, defaulting it to
72 columns and enabled.  Also add a configuration option to
"Settings->Version Control" for toggling the margin and setting its
width.
Remove duplicated editor setup
Use spinner control for VcsCommitMessageMarginConfigurable
Default commit message right margin to off
Refactor EditorTextFieldProvider to support more features

Replace the EditorCustomization.Feature enum with an EditorFeature object
which can support richer customization than "enabled/disabled".

The catalyst for this change was the addition of RightMarginEditorFeature
which needs a right margin size in addition to "enabled/disabled"
Restore commit message editor configs

Restores the soft wrap enabled and additional page disabled editor
settings to the commit message editor.

Also reverts accidental change to SDK in misc.xml
Use spinner control for Code Style->General right margin
adjust right margin code style setting spinner size: it was too wide
Refactor-simplify EditorCustomization & EditorFeature structure

* Merge EditorFeatures to EditorCustomizations, and remove the first.
  Motivation: EditorCustomization and EditorFeature serve the same
  purpose and thus introduce unnecessary duplication.

* Remove EditorCustomization extension point, since all customizations
  can be achieved via EditorTextFieldProvider#getEditorField.

* Let EditorCustomization be an interface.
  Extend on/off EditorCustomizations from SimpleEditorCustomization
  and provide ENABLED/DISABLED static instances to avoid creation
  of custom objects each time.

* This change introduces dependencies in vcs-impl and git4idea to
  the spellchecker module.
IDEA-101087 IntelliJ IDEA does not override MAVEN_OPTS when VM parameters for Maven runner are specified
correct cache control
Color Picker (internal action) +review
trim profiles name
cleanup
NPE