bug#3395: 23.0.94; Remove colon after option etc. name

[martin rudalics]

> A colon is a symbol consituent. A command that picks up the symbol at
> point will conveniently pick up the variable etc. name, but it will
> also include the colon (assuming that it correctly respects Lisp
> symbol syntax), which is incorrect.

Maybe we should improve or expand the regexp of `variable-at-point'

      "\\`\\W*\\(.*?\\)\\W*\\'"

to strip _any_ symbol characters surrounding a word-bounded substring at
point.  Or add yet another condition with a laxer regexp.

martin