general:
*   Start writing documentation concerning various implementation defined
    behaviours of the library.

math.h:
*   exp
*   exp2
*   expml
*   log
*   log10
*   log2
*   log1p
*   pow
*   cbrt
*   hypot
*   atan2
*   erf
*   erfc
*   tgamma
*   lgamma
*   frexp
*   ldexp
*   M_* constants
*   M_E
*   M_LOG2
*   M_LOG10
*   other stuff?

stdio.h:
*   The only reason to keep a linked list of all streams is to make sure they
    are flushed after main() returns. I wonder if only remembering the files
    with a buffer would increase performance.
*   Formatted print, scan

stdlib.h:
*   Strtod base 16 must be correctly rounded
*   Multibyte string functions
*   Better PRNG

threads.h:
*   TODO: add todo items

wchar.h:
*   Basically everything