Add libpeas support for currency conversion extension management
With !64 (merged) merged we have the base of the currency conversion "providers" generic enough to be able to support plugin management. The next steps towards #190 are:
- libpeas support for extension management
- two initial plugins for the existing providers (IMF and ECB)
- an API description (the current provider interface is a good start) for implementing new currency provider plugins
Edited by Robert Roth