Remove support for t_gI for now.
Remove support for t_gI for now.

It's odd to support just that Vim extension even though its implementation is
correct and that of t_I is not.  We should look at adding these commands later
when the core Vi commands are more accurately implemented.

--HG--
extra : rebase_source : f33cc9c9cbe0de8af2640655c0c7f9485f0a8a9d

madand/pentadactyl-pm,madand/pentadactyl-pm,nathyong/dactyl,moonshadow/dactyl,nathyong/dactyl,moonshadow/dactyl,5digits/dactyl,5digits/dactyl,5digits/dactyl,5digits/dactyl,nathyong/dactyl,5digits/dactyl,madand/pentadactyl-pm,airodactyl/dactyl,airodactyl/dactyl,Kjwon15/dactyl,Kjwon15/dactyl,nathyong/dactyl,invl/dactyl,Kjwon15/dactyl,Kjwon15/dactyl,5digits/dactyl,invl/dactyl,madand/pentadactyl-pm,invl/dactyl,nathyong/dactyl,airodactyl/dactyl,airodactyl/dactyl,moonshadow/dactyl,moonshadow/dactyl,invl/dactyl,invl/dactyl,moonshadow/dactyl,madand/pentadactyl-pm,invl/dactyl,airodactyl/dactyl,nathyong/dactyl,madand/pentadactyl-pm,Kjwon15/dactyl,airodactyl/dactyl,moonshadow/dactyl,Kjwon15/dactyl