Make licence explicit.

It is GPLv3 as per the conditions of the source code dump from Epsitec

closes #79
Render README with Markdown.
Fix canonical URL for colobot repository in README
Fix Markdown render, write changes down in Changelog.
Refactor archive creation.
Make releasing a git-linear process

- Git tag releases
- Amend README and Changelog for the release
- Prepare the next developement phase
Drop translations as they are built from colobot itself.
Convert all text files to Unicode
Drop leftover ws_ftp.log file
Transform CRLF to LF line endings

Used GNU sed: sed 's/\x0D$//' -i *.txt */*.txt */*/*.txt
Merge pull request #2 from OdyX/dev-unicode-crlf

Convert text files from ISO-8859 with CRLF endings to UTF8 with LF endings (Unix-standard)
Add initial CMakeLists file
Add script to extract translatable strings from level files
Add initial translation infrastructure
Update all level files with the new translation infrastructure
Add ScriptName to the list of translatable strings
Revert fuckups from previous commits
Make all translatabale strings level-specific
Update all level files with the new translation infrastructure
Split po4a configuration in categories

This has the advantage of dividing the translation in logical blocks
that are then dispatcheable amongst different translators.