request to fix and features

ok plugin, does what it says but can be a bit better

1.
on monthly reccurrent payements we ca see (p/m)
i imagine this means per month, however i think that this is not clear for everyone. can be

2. on “DONATE ONCE ONLY” interface
there is no information of selected “currency” that is confusing for people.

DESIRED FEATURES
3. small shortcode for choosing currency would be cool, at least : US, EU, GBP

4. a redirect to a thank you page after successful payement

5. anual payement options

p.s.
i will keep it a bit, but i think i will look for another options. As 2) and 3) seems to be critical