Fixed extra space after escaped spaces.
Really fixed extra space after escaped spaces.

Updated tests.
TeXMath Writer: EStretchy is reinterpreted as \\middle

This might need some tweaking and changes to other writers.
MathML Reader: Now uses EDelimited to match braces
Various: Removing EStretchy from source
TeXMath reader:  removed undefined in Delimited, added 'fence' helper.
Removed EStretchy from Types.