[conformal/btcscript] c0c3d8: Convert all StackErrX to ErrStackX.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcscript
  Commit: c0c3d860d693c9d477c9d7c2ef8784c4b7b4c041
      
https://github.com/conformal/btcscript/commit/c0c3d860d693c9d477c9d7c2ef8784c4b7b4c041
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-10-12 (Sun, 12 Oct 2014)

  Changed paths:
    M doc.go
    M internal_test.go
    M opcode.go
    M opcode_test.go
    M script.go
    M script_test.go
    M stack.go
    M stack_test.go

  Log Message:
  -----------
  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.