- added Release configuration in VS projects

- review of compiler an linker options
- VC .exe files are generated in bin_vc directory, not to interfere
  with binaries generated from other projects (cygwin, mingw, bcc ...)

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@2080 4a8a32a2-be11-0410-ad9d-d568d2c75423