Remove some NativeMML work-arounds for FF >= 29 (apparently fixed in this version).  Resolves issue #813.
Add semantics annotation to NativeMML output.  This is done in the NativeMML output jax rather than the input jax so that it can be done for any input format (that provides an encoding for it).  Also, it avoids having the Show As MathML output include the annotation.  Resolves issue #814.
Merge branch 'issue813' into v2.4-beta.  Issue #813.
Merge branch 'issue814' into v2.4-beta.  Issue #814.