For #34 and #48: Always update tags for current file on save

Remove variable ggtags-global-always-update.
Fix #52: Search references and symbols in GTAGSLIBPATH
Doc and indentation fix

Fix indentation for cl-labels and ggtags-with-current-project.
Fix FORMAT arg to with-demoted-errors.
For #52: new var ggtags-global-search-libpath-for-reference

Update NEWS for 0.8.4.