Compat wrapper methods

[VictorKoenders]

Made sure the Compat01As03 and Compat03As01 wrappers have the following methods:

• get_ref
• get_mut
• into_inner

Closes #1704

[VictorKoenders]

The pipeline itself seems to time out:

creating directory /home/travis/.cache/sccache
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated

[taiki-e]

@VictorKoenders Could you rebase? I think the issue of ci was fixed by 08dfdc6.

[VictorKoenders]

Rebased onto master (I think, someone double check that for me, git is arcane)

[Nemo157]

LGTM