Remove XHTML namespace from extensions generation.
In the WEBGL_security_sensitive_resources extension, use the term "secure sampler" instead of "security sensitive sampler" for clarity.
Merge pull request #421 from grorg/remove-xhtml-xslt

Remove XHTML namespace from extensions generation.
Merge pull request #422 from mvujovic/use-secure-sampler-naming

[WEBGL_security_sensitive_resources] Use the term "secure sampler" instead of "security sensitive sampler" for clarity