Feature request - support "move to parent" action for the main view

[chenkaie]

Take below graph for example, under "Main view", I thought that when I press , (move to parent) key on the view of b0d721f it will navigate to c1d1f71, but not happen :(
If "parent" key can support on "Main view", that will be truly awesome and handy.

Though this is not a good example, since this 2 commit are really near.
However in some case, it's really far away.

And also to handle a Merge commit as below

commit cafafe9e7dcd69157bb50d185ca13dc3f42d2873 (HEAD, origin/master, origin/HEAD, master)
Merge: bcc4484 b0d721f
Author: Jonas Fonseca <jonas.fonseca@gmail.com>
Date:   Wed Mar 11 20:00:48 2015 -0400

    Merge pull request #386 from andreasstieger/master

    Update FSF addesss in COPYING

Should provide somewhat like below I guess for a more convenient navigation
1: jump-to-first-parent
2: jump-to-second-parent

[chenkaie]

AWESOME!!! 👍