Rebase & Squash the English Rework

[eXpl0it3r]

This PR essentially supersedes #12 and #11

Additionally, it includes three commits from @akrinke's clone https://github.com/akrinke/Schiffbruch

The commits from #11 were mostly squashed as on their own it made it near impossible to properly rebase the work.
Additionally, I've included the reworked CMake and GitHub Actions changes from master.

Done in this PR:

• Rebase onto master
• Fix CMake build
• Remove Appveyor
• Generate *.cpp and *.hpp files with resgen, so we don't need C support

Things that might still closer investigation:

• The rescue percentage text sticks out of the banner and never vanishes from the screen
• Get the Linux build building (again)
• Cursor is rendered behind the "Ja" / "Nein" buttons
• Somehow never get a branch while play testing
• Did it always switch between night and day view when showing the text banner?
• Do we already want to change how the credits look?
• Review the non-refactoring changes in this PR
• when starting a new game, I still have the material from the previous game. Work around: quit the game, delete save.date (in the current working directory), start the game
• there is no mark on the map
• disabling water animation hides fields
• start animation often does not play properly on game start. Moving the mouse shows it. It does more likely when starting a new game.
• when landing with the boat in an edge of the corner, the boat sometimes lands on the wrong edge and a tree is removed or even the river delta (beach with river)
• man walked once out over the water, before leaving the game (by ESC or btn)
• Reapply wanted formatting