various improvements, fixes, and optimizations

This release introduces the following changes:

• slashes are converted to backslashes in the module name, and it is also quoted if necessary
• environment variable names are now properly handled in a case insensitive way
• process termination when stdin is redirected is now slightly faster
• the callers have been separated in two different binaries: one for wrun and one for wcmd/wstart (which executes wrun with an updated command line)
• outbash.exe is now built with additional security checks (provided by MSVC 2015 and Windows 10)
• MSVC's std::thread has been replaced with "mingw.thread.h", saving ~ 200kB in outbash.exe

To install from the binary archive, copy outbash.exe where you want.

Launch a "Bash on Ubuntu on Windows" session with outbash.exe, and from your unpacked archive directory launch sudo ./install.sh (this will put the WSL wcmd/wstart/wrun commands in /usr/local/bin)

Enjoy!