Fix image loading

Fixing issues when trying to load specific OpenEXR files and HDR files.

OpenEXR

TinyEXR header contained a bug. Replacing the content with the latest version solve the bug from https://gitlab.inria.fr/adufay/SpectralViewer/issues/3

HDR

Function for parsing header was not following the specs. It was expecting FORMAT tag at the last position. The spec does not enforce such order. Changed the parsing code responsible for this. Fix: https://gitlab.inria.fr/adufay/SpectralViewer/issues/2