Changes on variables grid for alignment

Using drop-downs on the wx.Grid don’t work well - crashes and a
less-than optimal experience. What I’ve done is made it text based.
Entering any part of ‘left’ (either case) will align left, any part of
‘centre’ will align centre and “right” for right align. This enables a
user to very quickly scoot through and set alignment for many variables
at once just by typing ‘l’, ‘c’ or ‘r’ as required. Any other value is
disregarded and the original displayed instead.