Fix constructor bug and make Wendland as a package class

 - Correct the mistake that Wendland(4) get a C6-continuous instance
Change WeightFunction.values more flexible

 - The parameter "dists" and "infl_rads" could be just iterable objects.
 - "dists" about nosetests seems well
 - "infl_rads" test haven't been build yet.
Build tests for dynamic influence radius for MLS, and pass it

 - also infers that the WeightFunction passed the tests
 - not that this tests is still very black-box
Refactor some functions' names in mls tests
refactor Wendland instance name and format weight_funcs.py

 - without refactor, Wendland won't run propoperly(Bug fix)
 - refactor self.diff_order to self._diff_order
Make and test CSRbf (Compactly supported radial bases)

 - make a simple test
   - this test also covers Wendland(4)
 - some complex test and written and commented for rbf convergence is not like mls