intersphinx failures & inconsistent docstring format

[jGaboardi]

Originally raised in #54, I have created a separate issue due to the scope of the solution. There are two parts to this issue:

• intersphix-mapping failures
  • PySAL weights object vs. libpysal.weights.W
  • PySAL weights object fails to create a link because it is not the actual class name
• overhaul of the doctrings
  • general overhaul of the doctrings for format, grammar, punctuation, etc. similar to ongoing project in libpysal
  • this is also would incorporate fixing docstring test failures (see #57)