Attempt to fix isfinite() checks to work with all C++11 compilers

[ojwb]

Fixes #615 and
#788

[wsfulton]

i like it, very neat solution. There is one potential problem I can see though. If the std namespace is not defined (which it may not be with just the math.h header include), then the using namespace std; will give a compiler error. This can be solved by adding in namespace std {} into the fragment, but I suspect that SWIG unfortunately, includes enough STL headers that std is defined somewhere, so may not be a problem in practice, even with with a minimal example.

Also, I think you should add SWIGRUNTIME to SWIG_isfinite_func to avoid linking problems when using multiple modules and %import.

[ojwb]

Good point about namespace std { }. For the second point, might be better to just make it inline, since it's just a forwarding wrapper so definitely wants to be inlined. Will address later this weekend (or feel free to push a commit to the branch).

[ojwb]

If the std namespace is not defined (which it may not be with just the math.h header include), then the using namespace std; will give a compiler error.

FWIW, this does not actually seem to result in a compiler error (tested with GCC and clang), though clang gives a warning which we want to avoid:

$ echo 'using namespace std;'|clang++-4.0 -Wall -W -x c++ -c -o /dev/null -
<stdin>:1:17: warning: using directive refers to implicitly-defined namespace
      'std'
using namespace std;
                ^
1 warning generated.

[wsfulton]

Let's go with this then. Indentation is conventionally 2 not 4 spaces though.