Visual Studio projects refactoring

[depler]

Changes:

• projects moved to subfolder vs
• projects created from scratch
• fixed release configuration in executable (code optimizations enabled)
• executable is statically linked (should work without any dependencies starting on Vista and newer)
• library contains configurations ReleaseMD and ReleaseMT (shared and static linkage)
• added 'vs\tests' subfolder with scripts for windows (uses original test files, see tests_bc.bat, tests_dc.bat)

By the way, did you test binaries on windows? I've found failed test for dc:

c:\Data\Sources\bc\vs\tests>tests_dc.bat
PASS: abs
PASS: add
PASS: arctangent
PASS: arrays
PASS: assignments

...

Parse error: bad character 't'
    <stdin>:2

FAIL_RUNTIME: vars

[gavinhoward]

I'm pulling this now because I made the fixes for all issues based on your code.

I'm probably going to need your help still.