Add check for prime moves without a space in between

[GuidoDipietro]

Let X'Y be a valid sequence, therefore the sequence is equivalent to X' Y, for any X: [FBUDRL](w)? and for any Y: move.

Easy fix: replace all ' with '\s except when the next character is a space or it's the last char in the string.

Also maybe change that part of the validation too completely (the RegEx check for spaces that updates as you type turned out to be a little bit annoying)

IMO all those replacements should happen after the user sends the solve and before it gets saved to Mongo.

I'll try to do it and if I can't I'll just buy a Cristóbal I guess.