renderTeX: Don't put space between letter tokens.
renderTeX:  Don't omit braces around single tokens.
Merge pull request #37 from mpickering/master

More changes towards the release
Added Text.TeXMath.TeX (unexported) with TeX defn.

Removed from Writers.TeXMath.
Make getTeXMath return [TeX] instead of String.

Also restored addition of brackets after certain commands
(e.g. accent commands).
Don't write identifiers as operators.

Cleans up a weird bug I introduced in an earlier commit.
Improved treatment of operators and identifiers.
Fixed bugs introduced by an ugly rebase.
Improve EText rendering.

Moved escapeLaTeX to TeX module.
texmath: Re-removed environment delimiters.
TeXMath writer:  Better handling of single-character identifiers.
Fixed order of overset and underset.
Fixed compiler warning
Fixed sign that was dropped in merge
Removed extra defn of isControlSeq.
Removed unused import
Test suite:  don't care about final newline in comparing output.
Test suite:  display failures only, and use diff.

This makes it easier to survey what has changed.
tex writer tests:  collapsed 2+ spaces to 1 space.

This should be semantically insignificant in LaTeX, and it
makes test output less crowded.
Test suite: name temp files for diff informatively.