Use LL for 64-bit literals

On a 32-bit architecture, these literals are too big for just a long,
they need to be long long, otherwise I get an error in GCC.
Change suffixes to ULL because Int64 is unsigned

As discusses in pull request #126
Merge pull request #126 from fnordware/LL_literal

Use LL for 64-bit literals
Use proper definition of namespaces instead of default values.
Merge branch 'develop' of https://github.com/JuriAbramov/openexr into develop