Wrap in `$` "eats up" initial digit

[henrison]

Highlighting a string of text beginning with a number, like 1.23 and then typing $ results in .23$ instead of the intended $1.23$.

A similar thing seems to happen with the "Wrap in" series of snippets (notably Wrap in Command), where executing the command on a string like $1.23$ results in \cmd{.23$} instead of the intended \cmd{$1.23$}.

Problem only seems to occur with strings starting with a digit. Hitting $ after selecting abc results in the expected $a1.23$

Possibly related to issue #82