STLplus C++ library collection SVN stlplus3

rework of theme and standardisation of title/headings

Summary: Updated docs to state that clang is a viable alternative compiler

Summary: Updating to match source code

reintroduced throw specifications on exceptions derived from system exceptions for backwards compatibility

added recognition of clang compiler

updated README with advice on accessing the SVN source

deleted accidentally added Visual Studio sln file

updated global ignores to ignore temporary and intermediate files

updated global ignores to ignore build folders

reworked release script to work with SVN and to be self-contained