Identify file using magic bytes instead of file extension

[mwestphal]

Is your feature request related to a problem? Please describe.
F3D is able to read many file formats and rely on the extension to identify which reader/plugin to use.
That works well however it has strong limitations:

1. How to discriminates between similar extensions
2. How to pick right reader when reading file from stream (Let F3D take as input a model via streaming rather than filename #1100)

Lets use magic byte logic to identify file format as well

Describe the solution you'd like
Use libmagic to identify files and check if a reader can read a file or not.
This may need some changes in VTK (CanReadFile) or may be a F3D only solution.