Add currency_cross type, fix bond type

• Add currency_cross type.
• Make bond type work. Requires to workarounds (remove country param for bonds, return "UNKNOWN" as currency if that column is missing in the returned dataframe) because bond types have issues in investpy. See also alvarobartt/investpy#572 and #5. Might later need to re-add the country for bond type when/if investpy gets fixed.

Adjust MIN_FROM_DATE, add commodity type

• Change MIN_FROM_DATE in investing from 01/01/1900 to 01/01/2010 so investing.com doesn't get hit with too many (sub)requests. Adjust MIN_FROM_DATE if you need data before 2010.
• Reduce the wait time for investing.com to 1s.
• Add "commodity", which was a missing type.
• Fix all kinds of minor issues.

Initial release

v0.1.0

Fix function name