Fixes path-separators on Linux

Also added some more files to .gitignore which are created
when actually running the software.

Fixed date in GlobalTypes.pas and changed version to 5.0.1.
Added missing file BlockedExtensions.txt

I have no idea how I could have missed this one... sorry!
Fix a bug with file-permissions on Linux

For some reason on Linux a file named "db2.url0" gets created with
execute-only permission. It needs to be read/write.

This workaround changes the file-permissions after the file gets
closed.

I don't know if this is something that I just don't understand
about Linux, or if this could be a bug in FreePascal?