Summary: Quick build test after apgrades to compilers, gcc v9 build
increment version after release
long-obsolete sample shared libraries, now use shared_library_test
Extra information about exception specifications
Release tag stlplus3-03-15
added changes for v3.15
just fixed indentation
updated to latest Win10 build
Retested on all platforms that I have access to
Slight changes to the links to Creative Commons
