removed broken minivect related code from branch since minivect will not be released as part of 0.18
set version to 0.18b1
undo code removal - not entirely clear what to make of it
remove references to 'minierror' module from Shadow.py
move exception class into shadow function as we may not want to export it under the cython.* namespace at this point
merge 0.18.x branch back into master
Added tag 0.18b1 for changeset c1a18ab6b080