Ideas: API changes and additions

[braydonf]

Since many of these haven't been touched, moving to the new repository and consolidating for overview:

Transaction:

• add Transaction.getSending/ReceivingAddress() (add Transaction.getSending/ReceivingAddress() bitcore#692)
• stardard g7 toBuffer/fromBuffer for input/output (Input/Output Standard Methods G7 bitcore#742)
• standardize Transaction.from (Apply G7 on Transaction bitcore#1013)
• shorten transaction.inspect output (Shorten Transaction.inspect output bitcore#1222)
• immutable transaction (ImmutableTransaction/Transaction Split bitcore#1224)
• add Transaction#allTo (add Transaction#allTo bitcore#1234)
• sighash api (Make sighash more useful? bitcore#1187)
• transaction's input's addSignature and getSignatures (Provide shortcuts to a transaction's input's addSignature and getSignatures bitcore#1105)
• sigtype/nhashtype from crypto.Signature and Transaction.Signature (Better handling of sigtype/nhashtype from crypto.Signature and Transaction.Signature bitcore#1283)
• Deserialize inputs into the correct subclasses when possible (Deserialize inputs into the correct subclasses when possible bitcore#1156)

Unit/URI:

• add Unit.isValid method (Add Unit.isValid method bitcore#978)
• chaining for URI creation (Improve URI api for creation bitcore#1197)
• Unit: "toX" methods should have a "string" version (Unit: "toX" methods should have a "string" version bitcore#1238)
• make Unit fail if initialized with undefined (make Unit fail if initialized with undefined bitcore#1127)

Block:

• Block/BlockHeader API improve block.header.prevHash (Block/BlockHeader API bitcore#1329)

Crypto/Keys:

• refactor crypto.ECDSA with nicer interface (Refactor crypto.ECDSA and expose an nicer interface bitcore#885)
• create a superclass for HDPrivateKey and HDPublicKey (create a superclass for HDPrivateKey and HDPublicKey bitcore#1090)

Errors:

• modularize errors (Consider moving custom errors to a seperate module bitcore#1257)
• expose a better base error class (expose a better base error class bitcore#1177)
• make all transaction errors instances of bitcore.errors (make all transaction errors instances of bitcore.errors bitcore#1178)
• Improve error message when attempting to spend a p2sh output without supplying public keys (Improve error message when attempting to spend a p2sh output without supplying public keys bitcore#1198)

Misc:

• add Chain constructor (New class: Chain bitcore#1150)
• move opcode.js inside lib/script (move opcode.js inside lib/script folder bitcore#1206)

[gabmontes]

Hi team! Any update on this? I'm particularly looking for bitpay/bitcore#1156. Thanks!