IOM: Localization/String improvements

* Switching mis-used B_TRANSLATE_CONTEXT to B_TRANSLATE_COMMENT
* Use B_TRANSLATE_SYSTEM_NAME for "Icon-O-Matic"
* Remove remnants of old localization system
* Rename "Control Points" to vertex/vertices
* Add a ":" after Undo/Redo
* Sentence casing
* Avoid Yes/No buttons in BAlert

Change-Id: Ibb299925bce1f6ca1cf03216a36df7c44f10bdc6
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6704
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

Icon-O-Matic: properly pluralize command names using BStringFormat

There are languages which have different plural forms than singular for one
and plural for everything else, and even if the number is not shown, having
the correct form looks nicer.

For NudgePointsCommand a helper function was introduced because there the name
is given as a constructor parameter.

Change-Id: I19a4984cf83af6612f2eafbf0920c9ad947d52ce
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6703
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

Icon-O-Matic: Generalize some classes

* Turns PathContainer, ShapeContainer, StyleContainer into Container.
* Makes Shape use Container for storing Tansformers instead of
reinventing the wheel yet again.
* Moves common logic from AddPathsCommand, AddStylesCommand,
AddShapesCommand, and AddTransformersCommand to AddCommand.
* Factors out common logic from two more commands similar to above.
This adds the MoveCommand and RemoveCommand classes.
* Cleans up some code style.

Change-Id: I59eca94a1c45eac608514f269f6e5f8628f93fab
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6640
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>