ENH: specific warning if matlab file is empty

Give a more specific and informative error when the matlab file is
empty.  Closes gh-4081
ENH: linalg: Add a function to compute the inverse of a Pascal matrix.
DOC: linalg: Add invpascal to the linalg package docstring and 0.16.0 release notes.
MAINT: linalg: Whitespace alignment.
MAINT clean up Von Mises code

Trimmed away dead code, used smarter Cython idioms.
MAINT/ENH various micro-optimizations Cython code

Meant to get more compact code, rather than extra speed (but some things
should get faster this way).
MAINT: small refactoring of matlab test

Just for neatness.
BUG: fix writing of logical arrays (gh-4022)

Fixes output type for logical arrays for MATLAB.

MATLAB apparently insists that logical arrays are in output type UINT8.
ENH: sparse: trim down _csparsetools

* Moved some non-looping, non-typeable code to Python.
* Merged three insertion routines, one templated, into one.
  The old single-value insert was converting to the right type,
  type checking, looking up a specialized routine through a dict,
  then casting back to object to do the actual work.
  The batch version skipped the dict lookup but otherwise did the
  same.
* Wrap-around and boundschecking turned off where appropriate.
* Various micro-optimizations.

                                  Old     New
Generated C LOC:                 45664   34220
.so file (MB):                    2.41    1.60
Compile time (wallclock, s):    10.667   7.781
Merge pull request #4012 from WarrenWeckesser/enh-invpascal

ENH: linalg: Add a function to compute the inverse of a Pascal matrix.
Merge pull request #4286 from matthew-brett/matlab-logical-matrix

MRG: fix matlab output type of logical array
Merge pull request #4213 from matthew-brett/empty-mat-file-error

ENH: specific warning if matlab file is empty
TST: clean up spatial.distance tests.

Removed unnecessary test docstrings, cleanup up the ones with useful
info in them.  Also removed commented out code, unused imports, etc.
TST: clean up cluster tests for docstrings and pyflakes issues.

Also remove unused file vq_test.py.
TST: clean up tests for scipy.misc.  Also remove unused import.
TST: some minor cleanups in constants, odr and fftpack module.
Merge pull request #4252 from larsmans/cython-maint

MAINT trim away >10 kLOC of generated C code
Merge pull request #4296 from rgommers/test-cleanup

MAINT: some cleanups in tests of several modules