Only initialize the fold settings when latex-box folding is really used.
Provide an option g:LatexBox_fold_text.

This option let users determine to use the FoldText function
provided by LatexBox or not.
Extract LatexBox_FoldText_title() from LatexBox_FoldText().
Fix section pattern for the title of folding.

Since it will match to the last brace of a line, the follwing example:

\section{a} \label{b}

becomes

*  a} \label{b}

rather than

*  a

The problem is fixed by changing the matching expression to match as
less as possible.
Merge pull request #187 from cwahbong/master

Improved LaTeX-Box folding and fold text