WIP ENH Picking normal orientation in beamformer solutions
STY Small changes
FIX Exception should be ValueError
Better picking of normal orientation in beamformer

Picking normal orientation by requiring the use of a surface oriented forward
operator and picking only normal components of the spatial filter. Also remove
previous code for projecting solution onto vectors normal to the cortical
surface and add one more test.
Updated docstrings with pick_ori parameter
Remove trivial check
ENH Add optimal orientation picking in LCMV

Also add three tests.
Compare orientation picking in LCMV example
Compare orientation picking in LCMV volume example
Move normal orientation calculation

This, in effect, turns the implementation into a scalar-type beamformer (i.e.
the orientation is already fixed when calculating the spatial filter, not
afterwards).
Modify normal orientation test

Because normal orientation is now enforced before and not after spatial filter
computation, the results aren't precisely smaller then for free orientation.
Clean up optimal orientation implementation
Clean up LCMV volume example
Clean up LCMV example
Mention orientation picking in example docstring
Small changes to docstrings

* Fix missing documentation of 'optimal' option for pick_ori
* Add reference for optimal orientation finding
* Add myself as author
Calculate lcmv solutions within a loop
Modify example for consistency and ease of viewing

* Make figures smaller for easy viewing on smaller screens and consistency with
  other examples
* Change colormap for consistency
* Activity plots now in a vertical alignment for consistency
* (also rename variable called boo...)
PEP8 fixes
Use eigh instead of eig for symmetric matrix