[Cbc] warnings about precedence

[Matthew Galati]

These warnings (esp first 2) seem worth fixing:

Warning    85    warning C4554: '&' : check operator precedence for 
possible error; use parentheses to clarify precedence   
 c:\cygwin\home\magala\coin\coin-decomp\cbc\src\cbcheuristicfpump.cpp   
 2374
Warning    100    warning C4554: '|' : check operator precedence for 
possible error; use parentheses to clarify precedence   
 c:\cygwin\home\magala\coin\coin-decomp\cbc\src\cbcmodel.cpp    8036
Warning    21    warning C4800: 'CbcBranchingObject *' : forcing value 
to bool 'true' or 'false' (performance warning)   
 c:\cygwin\home\magala\coin\coin-decomp\cbc\src\cbcheuristic.cpp    1068