Support stacktrace on Windows

adds 'strace_win' CONFIG option
Fixes: 1) Building fails w/o  "CONFIG += strace_win" 2) mingw build

Commenting Mingw release flags section for now. Strace is not reliable with mingw (only calls to other libraries are resolved, internal calls show up as addresses).
Refactor windows installer script to accomodate further translation. Also split it up so it is easier to maintain and extend.
Create language tables for all the available languages.
Updated translations.nsi
Support adding of windows firewall rule.
Change title of installer to show the qbt's version.
Split removal of configuration files to 2 options.
Add version info to the installer executable.
Add more info to the system about the unistaller.
Offer to launch qbt after installation.
The installer now checks if qbt is running before proceeding.
Run unistaller silently before proceeding with the install.
Added some logging for a few actions.
Reserve dll for faster execution.
Remove file associations only if qbt is associated. Fixes issue #307.
Updated language tables with all the strings.
Remove unused label.
Move the check for already running instance just before the actual installation.
Include third party plugins used by the scripts.