Added the source directory to all the search paths
Replaced packages with a DPK file for old Delphi versions and a group for newer Delphi versions.
Updated all include files
- Split the Lazarus demos directory into "Lazarus_Windows" and "Lazarus_Linux".
- Added OSRExternalPumpBrowser and TinyBrowser2 demos to "Lazarus_Linux".
- Set TBufferPanel.GetScreenScale as virtual.
- Added DevTools to the SchemeRegistrationBrowser demo.
- Modified the SchemeRegistrationBrowser demo to receive XMLHttpRequest requests from JavaScript.