- fbc: internal add AST_OP_BOOLNOT logical unary operator
- gcc backend: used internally by gcc backend for emitting the logical not '!' operator
- gas SSE backend: add operation to load Boolean from Float
- gas SSE/x86 backend: check parity (NaN) on Float to boolean conversion, extra check is removed
  when using '-fpmode fast' and enabled in '-fpmode precise' (the default).
- test-suite: add test for float to bool

The intent with this change is have cbool(float) behave consistently across all targets
- cbool( float ) is FALSE if and only if float = 0.
- For any other value (including NaN's) cbool(float) returns TRUE