Unmap Space in Select mode

Select mode is like insert mode. If I don't unmap, I cannot use space to
replace placeholder text in a snippet.
Use Runtime to source current script

Runtime disables load guards. Otherwise I comment out finish, forget I
did so, and check it in.
sub: Replace hiinterestingword with mark.vim

Mark.vim is actively maintained (although not on github) and has more
features than hiinterestingword.

I've modified mark.vim to allow disabling of maps, so use my repo.