1. Switched to Modern UI 2.
2. The Matroska logo is used during uninstallation as well.
3. Cleanup; moved code blocks around.
4. Changed the branding from the standard "NSIS installation system..."
string to something with "mkvtoolnix...".
5. Prepared the code to contain a build number in the product name;
the build number is empty for releases and will be set for pre-builds
by my automated build script.
Fixes for bug 327.
Removed old functions and replaced them with calls
to builtin/provided newer functions. Requires NSIS 2.42
or at least a System.dll plugin with the "Call" function
compiled in.
Part of a fix for bug 327.
