Split ext.visualEditor.experimental into specific modules

Math, hiero, language and alienextension are now each in their own
module. Kept the experimental module for backwards compatibility,
it just has all of its constituent modules as dependencies.

MWExperimentalTool.js was split up, and ExperimentalTool.js was
renamed to LanguageInspectorTool.js.

Change-Id: I63b49dfbdb59dc9a494049553cc0c01e89e48826
Merge "Split ext.visualEditor.experimental into specific modules"