Fixed FP function names in Python API.
Fixed FP function names in Python API.

Fixes #264

seahorn/z3,mschlaipfer/z3,mschlaipfer/z3,conceptofproof/z3,conceptofproof/z3,kyledewey/z3,wujunzero/z3,conceptofproof/z3,conceptofproof/z3,mschlaipfer/z3,wujunzero/z3,conceptofproof/z3,seahorn/z3,seahorn/z3,wujunzero/z3,wujunzero/z3,kyledewey/z3,mschlaipfer/z3,seahorn/z3,kyledewey/z3,kyledewey/z3,seahorn/z3,kyledewey/z3,conceptofproof/z3,kyledewey/z3,seahorn/z3,mschlaipfer/z3,wujunzero/z3,mschlaipfer/z3,wujunzero/z3