Added .gitignore file

Based on Delphi.gitignore from https://github.com/github/gitignore
MIT license Copyright (c) 2014 GitHub, Inc
Imported 3rd party code on which project depends into repo in Vendor sub-directory and added to project file.

This change means that the project no longer has any external dependencies.
Modified compiler path to exclude location of required library code & removed associated macros.

This is no longer needed because there are no more external dependencies.
Modified install script to make minimum compiler Windows 2000.

This is necessary because version of Inno Setup being used (5.5.2) no longer supports Win 9x or NT before Win 2000.

Consequence is that although program will still run on Win 9x and NT 4, installer won't.