feat: extract metadata from file names

[ycexiao]

Problem

The idea is suggest from diffpy/diffpy.morph#169

It is often the case that some metadata is not contained in the header but in the file names because the instruments and softwares generating the headers may not know some variables we are controlling, e.g. temperature, concentration of the components. These information is recorded in the file name manually for the convenience. Letting program processing the file names can help to automate the data processing step.