Add CMake-Po4a-based infrastructure to allow po-based translation of Colobot help- and scene-description (level) files
Add the help/ and levels/ CMake machinery to enable the po-based translations
Move level scenes to level-specific directories
Correct the Polish files capitalisation to be uniform across languages
Move help files to level-specific directories

Instructions
SoluceFile
Satellite
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Add translation files for all levels
Move the generic helpfiles into categories: generic, object, bots and cbot
Add translation files for all categories
Merge pull request #6 from OdyX/dev-level-help-translation-infra

"Help" files and "Level scene description" files gettext-based translation infrastructure