devtools: gosh: switch from Logf/Fatalf to TB, and related

This change makes most of the changes described in the final
proposal in https://v.io/i/1128 - namely, it makes all the
requisite API changes.

Things not done in this change:
- "Good PC" logging
- Printing Cmd stdout/stderr on failure

Those will be done in subsequent changes.

MultiPart: 3/9

Change-Id: Ie6d2e1131cc56c0a5c728cca6cab269f8c2a4d13
3 files changed
tree: a25879c0e94532d13c4d689905f1c66fee3a400f
  1. doc.go
  2. exec.go
  3. madb.go
  4. madb_test.go
  5. name.go
  6. name_test.go
  7. start.go