Preparations for Windows native MinGW build
Windows setup script working
Fixed some leftovers in the cross compile setup scripts
Tweaked Windows build setup scripts

* Added some informative output
* Use Copy-Item instead of robocopy to avoid admin requirements
* Download precompiled bjam so that no preinstalled compiler is needed
* Added popup message when done
* Fixed directory browser dialog not opening in shell enviroment
Merge branch 'Daniferrito' of https://github.com/Nimbal/Thrive into Daniferrito
Another round of build script tweaks

* Added archiver to toolchain file
* Clarified readme
Fixed build setup script not copying mingw correctly
Merge branch 'Daniferrito' of https://github.com/Nimbal/Thrive into Daniferrito
Fixed boost/install.ps1 looking in the wrong directory for 7z