Changed TxIn.PreviousOutpoint to TxIn.PreviousOutPoint after btcwire API change.
comment:script.go: ScriptDB->KeyDB
Fixed SignTxOutput doc spelling error.
Made hashType typed as SigHashType.
Convert all StackErrX to ErrStackX.

This commit changes all stack errors from the form of StackErrX to
ErrStackX which is the expected form for standard Go code.
Comment ScriptInfo struct according to standards.

Found by golint.
use btcec structs instead of ecdsa structs
Removed unnecessary signTxOutputCustomReader.
Merge remote-tracking branch 'conformal/master' into confmerge
ppc: #TODO internal_test.go: tests disabled - testdata port required
example_test.go: address fix
Merge pull request #1 from mably/confmerge

ppc: merged conformal/master, tests FAIL #TODO