Fix binding KP_NUMLOCK

Restore mapping SDL numlock to quake3 numlock.
Get clipboard data from SDL

This makes pasting in client console and UI edit fields work on X11 and OS X.

Sys_GetClipboardData is only used by client, so returning NULL in dedicated is fine.
Bullshit change to test jenkins configuration
Fix some warnings
There have been 0 days since the last compiler warning
Add cppcheck stage to jenkins script
Link instead of copy
Show environment variables from jenkins
Use scan-build when invoking clang
Merge remote-tracking branch 'ioquake3/master'

Conflicts:
	jenkins-ci-build.sh