Fix void edit_delete()'s behavior

The new behavior is if there is a selected text to delete it, otherwise erase the character immediatly following (if any)
XLib: Map keypad numbers for line edits
Merge branch 'tux3'
Merge branch 'numpad' of https://github.com/tux3/uTox into tux3-numpad
Merge branch 'tux3-numpad'