Create beta version of SPCode

[maxijabase]

This pull request describes the following modifications for SPCode:

• A new version of the program has been created, called SPCode Beta. It will receive updates everytime a new release labeled as "pre-release" is published, and it can be differentiated from the original by its new icons.
• The stable version of SPCode has been modified to only take updates from the stream of releases that are NOT labeled as pre-release.
• Both versions now include their .dll files embedded into the executable, which means less files to juggle around and less cluttered installation directories. If you wish to delete all of the .dlls next to the new executables, the program will continue working as normal.
• The program first downloads the Updater and the Portable version (the .zip file), and then executes the Updater, which looks for the .zip file, and unzips its contents in the installation directory (TODO: don't override sourcepawn folder) Done.

WIP