Merge branch 'release/0.3.3' into develop
The next version is 0.3.4
TODO: triage
setup: fixed version requirement for PyCUDA
fft.mako: removed commented code
TODO: more triage
fft.mako: not rendering some redundant conditionals

Technically they do not do any harm, but the compiler gives warnings.
Replaced int/unsigned int with SIZE_T and VSIZE_T, depending on what functions were used to get IDs.
doc/introduction: fixed MatrixMul parameter names
TODO: change of types does not seem to break anything, removing the task
helpers: refactored factors()
cluda/cuda: moved local size finder to a separate function
cluda/vsize: first approximation of the new algorithm
Added a test for group_dimensions()
More debugging of vsizes
cluda/vsize: wrapping sizes in tuples
cluda/vsize.mako: added virtual_global_flat_size()
test/cluda/cluda_vsizes: removed obsolete test parts
Some doc fixes for vsizes
TODO: updated