Feature/zi issue 152

[nielshaandbaek]

Fixes #152.

The logic associated with error handling has been changed slightly. First, the general error checking routine no longer reports the number of new errors, as this information is implicitly delivered when the actual errors are reported. In addition, the functionality also interfered with the functionality to ignore errors, i.e. new errors would be reported even if they were on the ignore list.

Second, the check_errors method now supports an optional argument that enables a temporary extra list of errors to be ignored. The functionality is used in the DIO calibration routine to now check for errors at the end, but to ignore DIO timing violations. In this way, we no longer clear the list of errors and it should not be possible to lose errors anymore.

@MiguelSMoreira could you have a look if this satisfies your requirements to fix #152?

In order for the pull request to be merged, the following conditions must be met:

• travis test suite passes
• all reasonable issues raised by codacy must be resolved
• a positive review is required

Whenever possible the pull request should

• follow the PEP8 style guide
• have tests for the code
• be well documented and contain comments

Tests are not mandatory as this is generally hard to make for instruments that interact with hardware.

[MiguelSMoreira]

@nielshaandbaek

I am not exactly sure how issue #152 relates to this pull request. Nevertheless, this is requested functionality that should be merged. To do so, I had to resolve a few minor conflicts, likely arising from the previous accepted pull-requests.