Handle mlabeledtr in Firefox and other browsers by making a more complicated table with extra columns.
Make the input TeX jax generate mrow+mo rather than mfenced.
Workaround mfenced support for Opera too ; add open/close properties on the element jax generated by the TeX/MathML input jax ; generate mfenced element for <mrow> elements with open/close properties.
Implement rowspacing/columnspacing for the native MathML output, using cell padding.
Some improvements to Davide's work ; make the rowspacing/columnspacing workaround work on Webkit too.
Merge branch 'issue356' into issue359

Conflicts:
	unpacked/jax/output/NativeMML/jax.js
Enable the mlabeledtr workaround for Opera
Rename some variables to follow Davide's convention ; use DOM element interface to browse the table.
Initial implementation of MathJax.Localization. Some experiments with French localization.
Trying to translate more dialogs ; Implement localization of numbers ; Handle arg substitution for arrays.
Implement the general HTML snippets substitution (e.g do the substitution in attributes too) + some small changes.
More attempts to translate messages.
Translation of messages from jax/input/TeX/jax.js
More translations...
Finishing to find all the strings to localize
Update more names to follow our coding style.
Experimental content-mathml extension.
Handle parsing of the <math> source better.
Implement the XSLT for IE <= 8.
Try to implement the XSLT transform for IE>=9.