implement "contains" function for strings
fixes
implemented substring search function: contains(haystack, needle)
extended logging
extended logging
Fixes #132. Numpy no longer required to install this package via pip, or from requirements file.
Fixed setup_requires.
working string "contains" operator
added str-two-way.h (substring search from gnulib)
Added requirements file.
moved str-two-way.h to correct location
Added (actully) requrirements file.
contains(s1, s2) works without malloc and free, added tests
pep8 correction
reorg preprocessor directives
used str-two-way.h version from newlib that has permissive, BSD-like license
cleanup
Merging contains branch
Moved str-two-way.h  to .hpp to follow numexpr conventions
Fixed a typo.