inline math completion without conflict with command completion.

Examples:
Type:
in line maths: $hello$,  \(world\)
Write to file, :up

To complete:
$ [part-of-hello] C-x C-o
\( [part-of-hello] C-x C-o
\[ [part-of-hello] C-x C-o

\( hello, $ [part-of-world] C-x C-o
\[ hello, $ [part-of-world] C-x C-o

\(
hello, $ [part-of-world] C-x C-o
\[
hello, $ [part-of-world] C-x C-o
\begin{eq-env}
hello, $ [part-of-world] C-x C-o

ATTENTION:
1.This one does not work:
$
hello C-x C-o
2. Do not try to compete in line math on the right of \begin{eq-env} in the same line.
It does not work properly if [part-of-eq] does not begins with \
    \begin{eq-env} hello, $ [part-of-world] C-x C-o

Even the following suggests nothing to complete.
\begin{env}  C-x C-o
( Because LatexBox_Complete function always first tries to find \ or { on the left of current cursor position,
and try to give a "begin" completion first.)