Fix ggtags-highlight-tag-map to avoid 'undefined' error

for example <S-mouse-1> is undefined.
Fix error: GTAGSCONF must be absolute path name

gtags complains if GTAGSCONF path contains ~, for example
~/projects/msc/.globalrc
New hook ggtags-global-next-error-hook

Reduce ggtags-project-duration to 600.
Trigger ggtags-update-tags based on visited file modtime
Use --color=always in ggtags-global-build-command

Required for windows and dos.
New customizable variable ggtags-mode-sticky
Doc fix