finalize, fix viz  bugs, address discussion

dont set meg/eeg cross cov to 0 + update example

address erics comments

revert picking @agramfort! and fix CTF support

address most of @Eric89GXL points + improve docs

fix failing viz test

fix bug with cross-cov, improve defaults for better num-stability

missing reject

viz bug if projs

revert example

fix scalinh

misc