Merge pull request #19 from dickon/master

Rewrite mkbuildmachine for simplicity and robustness.
winbuild-installer.ps1: Remove proxy nullifier

Removed line that nullifies system proxy. Not sure why this was there, but can do builds on open internet and behind proxy without this.
Merge pull request #23 from pearsonk/master

winbuild-installer.ps1: Remove proxy nullifier
Restore makecert script