Start updating tx21 description
more updates to tx21, more needed
The bulk of tx21 description updates
Tx21 description updated, plus other cleanup

Version and doc history to be updated.
clarified sort order for tx21 applying existing orders
added blocktime to the sort for matching tx21 orders
clarified tx21 unit price calculation, and other clean-up

Please give this a close read to make sure the whole tx21 description is correct.
Intermediate update after group review

still needs:
* .3% liquidity bonus
* rounding up for fractional quantities of indivisible coins
intermediate clarification of tx21
another interim save
clarified liquidity fee, rounding for tx21
fleshed out Send to Owners (tx3) descriptioin

* renamed from Send to All
* relocated from Future section
* added implementation note for distributing coins (per J.R.)
removed obsolete paragraph about Send to Owners
Match specw/code append/replace not yet supported
added transfer fee for tx3 - Send to Owners
Cleaned up Send to Owners after group review

doesn't include doc-wide changing:
* currency to property
* coin to token
Merge pull request #217 from marv-engine/send_to_owners

fleshed out Send to Owners (tx3) descriptioin
clarified tx3 Test MSC fee, sender sole owner invalid
Merge pull request #227 from marv-engine/clarify_tx3

clarified tx3 a) Test MSC fee for Test ecosystem currencies, b) if sender is sole owner then invalid
added liquidity bonus examples, fixed liquidity typo

removed satoshi reference