Add docs for pool.go
Merge pull request #53 from gsalgado/vp-doc

Add docs for pool.go
Add missing doc comments, remove redundant serialization descriptions.
Got agreement from dave on the second point.
Change as per Jimmy's review.
More changes per Jimmy's review.
One more.
Added two examples.
Merge pull request #51 from teknico/vp

Add missing doc comments, remove redundant serialization descriptions.
Added doc comments to internal_test.go
Also moved two tests away from internal_test.go to pool_test.go (no actual test code in the former).
Put those two tests back in internal_test.go .
Merge pull request #54 from teknico/vp

Added doc comments to internal_test.go
New test for another error case in DepositScriptAddress