files with with weird extentions may get mistakenly recognized as a wrong file type.

[omar-azzam00]

We should split the values of both the dictionaries datatypes and icontypes to a list so that a file with an extension like 'if,ic' doesn't get mistakenly recognized as an image file.

This happens due to this code which checks against a str not a list:

@app.template_filter('data_fmt')
def data_fmt(filename):
    t = 'unknown'
    for type, exts in datatypes.items():
        if filename.split('.')[-1] in exts:
            t = type
    return t