Partial commit starting changes for doc fixing
first version of export_pickle, tests need fixing
fix mocking (we now use __builtin__.open)
Remove missing classes

Features, landmark functions and other classes are still very
broken, but this removes fit, fitmultilevel and rasterization
fixes some imm_face landmark group
Fix some minor docs in Image
menpo.io.input.base moved to use pathlib
remove redundent methods (should be in menpo3d)
Merge pull request #520 from patricksnape/docs_fixes

Documentation fixes
pickle importing added
added docs for pickling
flip export methods args to (obj, fp)-match pickle
Move viewer into view method for alignment
Documentation isn't building on RTD

Move some module imports around
Add more cython modules to documentation ignore
Add pathlib to rtd requirements, remove unsued file
add pickle unit tests
Merge pull request #521 from jabooth/export_pickle

menpo.io add pickle support, move to pathlib