ENH: define addition/subtraction operations for scalar and complex
- required since construct complex from scalar is explicit
- additional tests in Test-complex
- operators are still incomplete, as are dimensioned fields,
field-fields etc.
- split complexFields into separate complexField, complexVectorField files
- add construction from and conversion to std::complex, which allows
easier wrapping of functions
- add Foam:: functions for complex versions of sin, cos, ...
- was historically defined as (1 1), but it is more consistent with
the concept of one to have a real component only.
Now defined as (1 0): 1+0i
STYLE: remove obscure '!' operator for complex conjugate
- either use the member function or the '~' operator