Added vim's .swp files to .gitignore

Also .gitignore now ends with an endline.
Removed old temporary file in Play
Removed execute permissions from files in Player
Huge rewrite of makefiles

Now there is one file with a lot of rules, which is included in small makefiles
in the directories. The small makefiles contain only a few local variables. The
makefiles can now also create libraries and link those created by other
makefiles.
Merge branch 'master' into bidding-rewrite