Wrong highlighting and indentation after a char that is an escaped quote

[ronisbr]

Hi!

If we have a char that is a quote ', then the highlight and indentation is not correct:

[recri]

Same thing, after this line:

            elseif c in ('\'', '\"', '\`')

entire rest of source file is rendered as part of a string.

[non-Jedi]

Don't know when I'll get to this but if someone else wants to take a shot at fixing, the rough outline of the solution is:

1. Give ' string delimiter syntax by default instead of operator (so that the logic for detecting whether \\ has escape syntax or operator syntax in julia-syntax-propertize-function works for it).
2. Instead of detecting that ' is the start of a string with julia-char-regex, detect when it's an operator.

[recri]

Opened a pull request that appears to fix this. julia-char-regex looked very obscure, but it was only wrong. Syntax table is unchanged.