Add WIP interface calc material, documentation stub

ERC20.txt

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+totalSupply()
+balanceOf(address)
+allowance(address,address)
+transfer(address,uint)
+approve(address,uint)
+transferFrom(address,address,uint)

contracts_overview.txt

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+Contract interfaces overview
+
+
+AccountRegistry
+
+* interface:
+* append-only list of custodial addresses 
+* only writers may add addresses
+* only owner may add and remove writers
+
+
+AddressDeclarator
+
+* interface:
+* enables addresses to link one or more 32 byte entries to another address
+* used for:
+	- kyc proofs to user account addresses
+	- token metadata (eg. tokenlists.org std), endorsements, warnings
+* freely writable
+
+
+Faucet
+
+* interface:
+* allows transfer of an amount of one particular token to a given address
+* transfer amount can be changed at any time. invocation will used the transfer amount set at the time.
+* anyone can invoke the function for anyone
+* implements a function to provide cooldown info, max(uint256) means cooldown disabled (one-shot only)
+
+
+Token Symbol Registry 
+
+* interface:
+
+* simple key-value store to enforce unique token symbols
+* only owner can write 
+* will check that token symbol reported by ERC20 interface matches provided key (case sensitive)
+
+
+Transfer Approvals
+
+* interface:
+
+* counter-signing of transfers from custodial addresses invoked by third-party (staff)
+* custodial address must create an allowance for contract
+* only "approvers" may reject/execute transfers
+* provides lists of open requests