drop HTMLCov and JSONCov reporters

[boneskull]

I mentioned this in Gitter, but both of these reporters leverage node-jscoverage, which is old and busted. It's my suspicion that these two reporters are rarely--if ever--used by anyone. Better coverage options exist in the form of istanbul, nyc, etc.

Furthermore, the only reason we have a dependency on jade/pug is these reporters.

I would like to drop them completely for v3.0.0, and remove the jade/pug dependency.

If anyone out there uses either of these reporters, please let us know!

cc @mochajs/core

[dasilvacontin]

Reporter usage statistics? :)

[boneskull]

Well, we won't know until we break it and someone tells us, but it is a major.

[boneskull]

closed via b47835b in v3.0.0 branch

[ScottFreeCode]

A bit late, but my 2¢'s worth:

• Using reporters that require a specific coverage tool does not scale well. Having a standard format for coverage to be output and (a) reporter(s) that use(s) said format, so we're not limited to specific coverage tools, would be far more maintainable.
• If there are adequate coverage tools that work with Mocha without a special Mocha reporter needed at all, then a reporter's not really a necessity.
• Mocha can take third-party reporters if I'm not mistaken, so if anybody wants/needs Mocha reporters that include coverage (including the existing ones), we/they can just package them separately.