Removed more duplicated code, and used type-specific data for callbacks
Removed more duplicated code, and used type-specific data for callbacks

Callbacks now use their specific struct gdata as their callback userdata,
which allows for some duplicated code removal in gc_sync_done() and
gc_connect*()

git-svn-id: 85993595adea9501c3608f1a84298b90251c745e@6122 53f5c7ee-bee3-0310-bbc5-ea0e15fffd5e

luizluca/google-calendar