LoadLibHAPI fails to find the installation folder

[vongkitt]

When the Houdini SDK is not installed (CI build for example), the heuristics always fail to find the installation folder. Multiple methods are being used but they might need to be updated.

Using Houdini 19.0.622:

1. Environment variables like HAPI_PATH and HFS but they are not set by default by the installer ?
2. Custom location, this is working but less than ideal because they are stored in DefaultEngine.ini which is used by everyone. Issue has been reported in another issue (#120 )
3. Registry lookup will fail because it is looking for Houdini or Houdini Engine but the registery key was Houdini 19.0.622. The code might need to be updated
4. Search in Program Files. This will fail because the plugin version set in HAPI_Version.h does not match the version installed.

You might want to update the code for 3 and 4.