Fix handling of single LPUNC tokens.
Fix handling of single LPUNC tokens.

The code supposed that when a token consists of only LPUNC tokens, no
more processing should be done - separate_word() just returned
immediately.

However, single LPUNC tokens may match a regex. So don't return in a
case of a single LPUNC token.

linas/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,MadBomber/link-grammar,opencog/link-grammar,opencog/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,linas/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,MadBomber/link-grammar,ampli/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,MadBomber/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar