Support for alpha4.

- New master branch. "master" branch is alpha4.
- Alpha3 translation was archived to "Alpha3" branch.

Memo:

Incomplete:
ConceptDefs.xml, Designators.xml, Gameplay.xml

Needs to replace Alpha3 def-file data:
Messages.xml, WorkTags.xml

Needs to confim on game:
FloatMenu.xml

Completed:
Alerts.xml
Credits.xml (Won't translete)
Designators.xml
DialogsVarious.xml
DialogTrees.xml
GameplayCommands.xml
Incidents.xml
Letters.xml
Menu_Options.xml
Menus_Main.xml
Menus_Overview.xml
Misc.xml
NoEffectTraits.xml
PlayInterface.xml
Pronouns.xml
Skills.xml