Improvements to spelling corrector

[arvindpdmn]

• Spell checker seems to stall on long text. However, due to Spelling and grammar correction #504 spell correction may be done on server side.
• Handle tech words
• Compress *.dic files
• BERT is ignored correctly because it's an acronym but when both BERT and bert are in the text, both are flagged as errors.

[arvindpdmn]

Tech dictionaries:

• https://techterms.com/category/technical
• https://stackoverflow.com/questions/29732381/dictionary-of-technical-terms-in-python

[arvindpdmn]

Compression delivered in V0.38. Others rescheduled.