Export an error for currency mismatches (Rhymond#91)

Co-authored-by: Raymond <[email protected]>

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

Merge pull request Rhymond#36 from Toasterson/patch-1

Add SwissFranc with proper Formatting

Merge pull request Rhymond#28 from hieven/fix/redundant-decimal

Fix redundant decimal when fraction is 0

Merge pull request Rhymond#26 from llonchj/feature/get-currency

GetCurrency implementation

Merge pull request Rhymond#24 from llonchj/fix-currency-money-New

A new instance of Money has invalid Currency contents