Support for synonyms

[donmendelson]

Applications based on Tablature depend on keywords in the markdown document. For example, md2orchestra uses keywords "message, "field", "component", and so forth to identify context. A question is how far Tablature apps should go with synonyms for keywords. In md2orchestra, "description" and "documentation" are already handled as synonyms. However, alternative terms have been used in FIX that might be used by many people. For example, a code could be described as "code value" and "symbolic name" instead of just "value" and "name". To be very flexible would require a controlled vocabulary with many synonyms.