Fixes visual mode selection for G and gg

MoveToLine's G selection code previously only moved a single line down,
which is not in line with vim.  MoveToStartOfFile was also only moving
a single line of code in selection mode.  This corrects both of these
selection issues.

![g_selection](https://cloud.githubusercontent.com/assets/28146/3076226/b752d1f8-e3c1-11e3-9e71-153a43f9853d.gif)