Added unary operations for vectors, prepared for matrices: element_sin(), element_cos(), etc.

Supported operations (prefix element_):
abs, acos, asin, atan, ceil, cos, cosh, exp, fabs, floor, log, log10, sin, sinh, sqrt, tan, tanh
Fixed a warning in forwards.h related to an unused typedef.

Showed up with GCC 4.8, reported by Toby.
clean up code
Merge remote-tracking branch 'upstream/master' into pyviennacl

updated upstream to fix warnings, merging..
re-enable pedantic compile flags