Add XOF and MGA currencies (Rhymond#110)

This patch adds West African CFA franc (XOF) and Malagasy ariary (MGA)
currencies in order to provide them in go-money library.

See also:
- [West African CFA
  franc](https://en.wikipedia.org/wiki/West_African_CFA_franc);
- [Malagasy ariary](https://en.wikipedia.org/wiki/Malagasy_ariary);

Closes Rhymond#109

Signed-off-by: r1cm3d <r1cm3d@protonmail.com>

Rhymond#106 Split of small negative values doesn't work properly (Rhy…

…mond#107)

Get Currency by Numeric Code (Rhymond#104)

* find currency by code

* get currency by code

fix negative split remainder (Rhymond#94)

Co-authored-by: Raymond <raima220@gmail.com>

Export an error for currency mismatches (Rhymond#91)

Co-authored-by: Raymond <raymond.kazlausk@gmail.com>

Merge pull request Rhymond#70 from nvjkmr/master

Added ISO 4217 numeric codes for currency

Merge pull request Rhymond#63 from danielwitz/mymaster

fixing TWD fraction

update travis versions

Merge pull request Rhymond#51 from danielwitz/master

Add currencies and add AsMajorUnits capability

Merge pull request Rhymond#42 from treezor-bank/1-create-go.mod

Add go mod