WebSupport places pickles outside specified datadir

[liborjelinek]

WebSupport class offers to specify buildir and datadir params (plus some others). Builddir param is optional (have default value ''). If you don't buildir but specify datadir, then files made during Sphinx build (pickles/ folder, files like environment.pickle or globalcontext.pickle) are not placed in specified <datadir> but in <current_work_dir>/data.

At sphinxcontrib.websupport in core.py:55 is introduced self.outdir

54   self.builddir = builddir
55   self.outdir = path.join(builddir, 'data')
56   self.datadir = datadir or self.outdir

that has only usage: it's passed to Sphinx constructor at core.py:125

125  app = Sphinx(self.srcdir, self.srcdir, self.outdir, self.doctreedir,
                  'websupport', status=self.status, warning=self.warning)

Proposed fix: IMHO outdir at core.py:55 line should look like this:

self.outdir = datadir or os.path.join(builddir, 'data')