Add support for VMWare Workstation on Windows XP, fixes #237

The `ProgramData` environment variable does not exist on Windows XP. I tested these changes in Windows XP and it works fine.

These changes also make the code more robust, by searching a series of locations for program files:

1. The `%PATH%` environment variable (VMWare Workstation does not appear to be in the path on Windows XP).
2. The `VMWARE_HOME` environment variable.
3. The location found in the registry.
4. The `%ProgramFiles(x86)%/VMWare/VMWare Workstation` folder.
5. The `%ProgramFiles%/VMWare/VMWare Workstation` folder.

And this series for data files:

1. The `VMWARE_DATA` environment variable.
2. The location found in the registry.
3. The `%ProgramData%/VMWare` folder.
4. The `%ALLUSERSPROFILE%/Application Data/VMWare` folder.