textproc/link-grammar: Update to 5.4.3

Changelog:
https://github.com/opencog/link-grammar/blob/master/ChangeLog

Additional port changes:

• Changed to DISTVERSION
• Added LICENSE/LICENSE_FILE
• Added USES=ncurses
• Added port options SAT_SOLVER,TOKENIZER
• Updated WWW with https URL

Approved by: tcberner (mentor, implicit)