Try to create "no land contact" version of usual objects using proxies

[jetelain]

Additional option for #292

Most "land contact" models have no alternative version. Proxies could be an option to create "no land contact" versions that is EULA compliant.

[jetelain]

Proxies works, but:

• textures are not rendered if object center is not on screen
• collision does not works as intended
• some models does not works