DER-130 - Further work in cleaning up lookback contract terms and other definitions in the Exotic Options ontology

[ElisaKendall]

Signed-off-by: Elisa Kendall ekendall@thematix.com

Description

1. Cleaned up lookback contract terms - eliminated redundancies including formulas that referenced expressions where only the expressions added value
2. Eliminated levels of indirection in calculating fixed and floating lookback expressions, reorganized strike terms and revised lookback strike terms to better incorporate the expressions, lookback window, and pricing history used for those calculations
3. Revised the definition of price structure in IND to add a synonym of price history, and added a new explanatory note and eliminated formatting issues in indicators; continued clean-up of exotic options per FCT discussion
4. Integrated definitions from the CFI standard where appropriate

Fixes: #1801 / DER-130

Checklist:

• [x] I'm familiar with the FIBO developer quide. My contribution meets all the requirements described there.
• [x] My contribution follows the principles of best practices for FIBO.
• [x] My changes have been reconciled with latest master and no merge conflicts remain.
• [x] This PR is related to exactly one issue. The issue is referenced by using a GitHub keyword such as "fixes", "closes", or "resolves".
• [x] Hygiene tests have been applied by a PR with "(WIP)" in title.
• [x] The issue has been tested locally using a reasoner (for ontology changes).