* same behavior for positive numbers
* generalisation for negative numbers, treating them as two complement
* improve algorithm, iterate once over the digits, manually perform two complement
* simplify mp_add_d, mp_sub_d
* functions are safe in case of a==c or b==c
* renamed mp_tc_div_2d to mp_signed_rsh (signed right shift)
* MP_USE_ENUMS enables enums
* Wc++-compat catches some implicit conversions if MP_USE_ENUMS is defined
* 100% backwards compatible API/ABI if MP_USE_ENUMS is not defined
* (!) Always zero buffer before freeing if MP_NO_ZERO_ON_FREE is not defined
* Add MP_NO_ZERO_ON_FREE to disable hardening
* Add MP_ZERO_BUFFER, MP_ZERO_DIGITS, MP_FREE_BUFFFER, MP_FREE_DIGITS
* Never use MP_FREE directly, use MP_FREE_DIGITS or MP_FREE_BUFFER
* Add MP_USE_MEMSET to use memset instead of loop
* Disable astyle backups which are annonying in the times of git
tommath.h contains declarations for the public part of the library.
tommath_private.h contains the functions which are private to ltm and
should not be exposed to the public.
