Add bigint library for floating point arithmetic in form validation
Add 'divisible' flag to /v1/address/addr/ endpoint
Add WHOLE/SATOSHI unit conversion (as BigInts) and logic to check if we need to convert to either unit based on divisibility of the Property/Currency. Wallet_send.html contains abstractions to modify the displayed value depending on divisibility.
Modify user-facing errors to report values in BTC versus mBTC and calculated in BigInt to avoid floating-point arithmetic errors. Simplify conversion logic to SATOSHI/BTC or BTC/SATOSHI, and force arithmetic to use BigInts. Add checks to ensure conversion is done only for those values that are considered divisible.