use SDL keycode for shortcuts (doesn't fix layout issues)

ingore moar keys

Add some flags for a few of the magic Land values

useless test

Key returned 0 for arrows under linux. Sym works, clearer anyway.

linux keycodes differ from osx's

use a local storage for chat history which prevents mix ups in netgame and simplifies code

less cryptic text insertion

gather a few common code

implement up and down keys to navigate in the chat history, needs testing over network

don't display squares when pressing arrow keys in chat

formatting

do not hardcode CMAKE_INSTALL_PREFIX for windows, but rather put it in the script, so that custom build setups still work

Hard math to fix issue #571. Well, not really hard math, just checking if vector is in opposite direction and trait that as a special case when removing rope dividing point (this could only happens when rope sticks to land outline, so this basically fixes a bug in another bug).