Merge pull request #45 from larshesel/vp

Add test of decryptExtendedKey error paths
pool_test.go reformatting
- uniformed all messages with actual value first, expected second
- clarified error messages
- made comments more readable
- shortened long lines

No functional changes.
Revised changes with Lars, should be more reasonable now. :-)
Oops. :-) Syntax errors fixed.
Merge pull request #44 from teknico/vp

pool_test.go reformatting
Add test for EmpowerSeries key neutering error path