L-functions and BSD

ELLFF

Done
- Made patch for Sage 4.4.2 (see: trac)
- RationalFunctionField support (see: trac)
To do
- Documentation and doctests
- Loading and unloading tables
- Local reduction for function fields
- Tweak Makefile

Tommy implemented heights over function fields using the intersection pairing on the associated elliptic surface. See code and patch