Drop single folder support by experiments

I consider putting everything into one directory bad practice.
Close experiment log right after the scan
Change root_directory to directory_format
Added acquisitions to experiments

This improves experiment modularity and flexibility.
Added acquisition tests
Acquisitions are swappable in experiments
Experiment acquisition swap test added
Added imaging acquisition routines
Added base class for testing experiments
Split base and imaging experiments tests
Dummy camera has default frame rate
Added imaging acquisition and tomography tests
Add argdrop function
Added argdrop test
acquire method added to dummy camera
Experiment docs update
Added flat correction to imaging experiments
Added flat correction imaging test