Refactor TextImages assessment

[nataliashitova]

We need to refactor TextImages assessment to accommodate morphology and synonyms.

GOOD if there is an alt-tag that contains a content word from the keyphrase or synonyms.
BAD if there are no images.
OK otherwise.

After the recalibration, the GOOD output will be specified as follows:
If < 5 images, GOOD if at least 1 alt-tag with the (content) word from the keyphrase or a synonym.
If 5 images, GOOD if 2-4 alt-tags with the (content) word from the keyphrase or a synonym.
If >5 images, GOOD if the number of alt-tags with the (content) word from the keyphrase or a synonym is within 30-75% range.