:bug: 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.
Merge pull request #272 from cadwallion/g_selection

Fixes visual mode selection for G and gg