Use bool_t instead of BOOL_T

One bool typedef is already more than enough, two is too many.
Use bool instead of bool_t

bool is one of the built in, standard types in C++, there's no need
for a typedef for it.
Use void instead of void_t

There's really no reason for adding a typedef for void.
Use char instead of str_t
Use the C++ constants true/false instead of defining our own

TRUE/FALSE has intentionally been left in use for the few
platform specific APIs that define these constants themselves
and expect them to be used, for consistency.
Merge pull request #274 from mstorsjo/typedef-cleanup

Remove typedefs for standard C++ types