Log Message:
ltm: update to 1.2.0.

Partially based on diff sent by Kai-Uwe Eckhardt in private mail.

v1.2.0
       -- A huge refactoring of the library happened - renaming,
          deprecating and replacing existing functions by improved API's.

          All deprecated functions, macros and symbols are only marked as such
          so this version is still API and ABI compatible to v1.x.

       -- Daniel Mendler was pushing for those changes and contributing a load \ 
of patches,
          refactorings, code reviews and whatnotelse.
       -- Christoph Zurnieden re-worked internals of the library, improved the \ 
performance,
          did code reviews and wrote documentation.
       -- Francois Perrad did some refactoring and took again care of linting \ 
the sources and
          provided all fixes.
       -- Jan Nijtmans, Karel Miko and Joachim Breitner contributed various patches.

       -- Private symbols can now be hidden for the shared library builds, \ 
disabled by default.
       -- All API's follow a single code style, are prefixed the same etc.
       -- Unified, safer and improved API's
       -- Less magic numbers - return values (where appropriate) and most flags \ 
are now enums,
          this was implemented in a backwards compatible way where return values \ 
were int.
       -- API's with return values are now by default marked as "warn on \ 
unsused result", this
          can be disabled if required (which will most likely hide bugs), c.f. \ 
MP_WUR in tommath.h
       -- Provide a whole set of setters&getters for different primitive \ 
types (long, uint32_t, etc.)
       -- All those primitive setters are now optimized.
       -- It's possible to automatically tune the cutoff values for \ 
Karatsuba&Toom-Cook
       -- The custom allocators which were formerly known as XMALLOC(), XFREE() \ 
etc. are now available
          as MP_MALLOC(), MP_REALLOC(), MP_CALLOC() and MP_FREE(). MP_REALLOC() \ 
and MP_FREE() now also
          provide the allocated size to ease the usage of simple allocators \ 
without tracking.
       -- Building is now also possible with MSVC 2015, 2017 and 2019 (use \ 
makefile.msvc)
       -- Added mp_decr() and mp_incr()
       -- Added mp_log_u32()
       -- Improved prime-checking
       -- Improved Toom-Cook multiplication
       -- Removed the LTM book (`make docs` now builds the user manual)