feat(API): Signal/Frame conversion mode

[epage]

Fixes #41

• This contribution adheres to CONTRIBUTING.md.
• New tests have been created for any new features or regression tests for bugfixes.
• tox successfully runs, including unit tests and style checks (see CONTRIBUTING.md).

[coveralls]

Coverage decreased (-0.6%) to 63.999% when pulling 8b06667 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling 3ef1c54 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling 3ef1c54 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling 3ef1c54 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling d1c2bd9 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling 5be0878 on epage:convert into 78bdf9b on ni:master.

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling 5be0878 on epage:convert into 78bdf9b on ni:master.

[epage]

This will be a step towards #9 and #88

[coveralls]

Coverage increased (+0.6%) to 65.157% when pulling c3008fb on epage:convert into 78bdf9b on ni:master.