msvc12/log4cplus.props: Raise default Windows version to 0x0600, i.e., Windows Vista.
src/socket.cxx: Avoid braced initializer to avoid #ifdef.
spi/rootlogger.h: Avoid symbol hiding warning with MSVC.
helpers/stringhelper.h: Remove comment that is no longer relevant.
Remove logloguser.h and logloguser.cxx from MSVC project files.
Set required Visual Studio platform to v140 (Visual Studio 2015).
Rename msvc12 directory to msvc14.
Split DLL and static log4cplus settings from log4cplus_tests.props into own files.
Add Visual Studio project files for static library log4cplus tests.
MSVC: Make log4cplus static library test projects use static .lib.
Revert most of 439414a49a07d7119f0a58b252a853e8e6fc4dab to avoid crashing
during startup when using static library log4cplus.
Ignore all .opensdf files.
Merge pull request #58 from wilx/master

Merge.