update reader for aps 1id data

[KedoKudo]

Add a new parser function that parses the metadata generated from the tomography experiment at APS 1-ID into a DataFrame, which is used in the reader function to automatically select different valid layers for tomography reconstruction.

[decarlof]

@KedoKudo I suggest to move

def parse_aps_1id_metafile(metafn): 

from exchange.py to reader.py and for consistency rename it as:

def read_aps_1id_metadata(metafn):

[decarlof]

@KedoKudo thanks!