Improve ability to use C SBP messaging libraries and headers with Microsoft Visual Studio

[denniszollo]

• Allow easier use of library from C++
• remove/replace any gnu specific keywords ( this stack overflow might be helpful) http://stackoverflow.com/questions/1537964/visual-c-equivalent-of-gccs-attribute-packed

[michaelaeriksen]

Any progress on this?

[denniszollo]

There are now macros wrapping the compiler specific flags for the #pragma and __ATTRIBUTE_PACKED so with one simple pre-processor switch you can use msvc.