WIP: Move formatters etc. into own file + tests

[dexX7]

All tests pass and building, using the client works as expected.

The Format__MP tests should cover almost everything, tests for strToInt64 were copied from zathras, rounduint64 has none.

strprintf was an alias for tfm::format in util.h which refers to tinyformat.h which seems to have many boost dependencies.

I'm not sure about function names. Upper case, lower case, ...?

Also note: FormatDivisibleMP and FormatIndivisibleMP were in namespace mastercore. If they should be in an explicit mastercore namespace, then I suggest to remove the MP suffix.

[m21]

Nice to have the tests as part of make fore sure.
I am not crazy about the "transformers" name. Maybe mastercore_format.cpp or similar?
I kinda prefer shorter filenames to long ones, but that's a very weak comment on my part.
Just FYI : I see that at Bitcoin master they are splitting util.cpp into: util.cpp utilmoneystr.cpp utilstrencodings.cpp utiltime.cpp

and need @zathras-crypto and @faizkhan00 on this as well. Thanks!

[dexX7]

Agreed, mastercore_format is a much better choice. It may also be considered to move into a seperate directory and get rid of the mastercore_ prefix. By using one or more namespaces, hints such as __MP() could be further removed.

[dexX7]

Replaced by #180, #182 and #183.