#1526 Enable ignore function when checking issues

[Erik De Boeck]

The translations of some segments break certain rules on purpose. A title, for instance, usually doesn't have ending punctuation.

The "check issues" (Ctrl + Shift + V) service of OmegaT marks this as an issue, while in reality, it isn't an issue.

In large documents, it can get difficult to remember which issues are actually not issues. This decreases the efficiency of "check issues".

I propose adding some features, inspired by Microsoft Word:
1. Adding the option Ignore this instance of this"issue".
2. Adding the option Ignore all instances of this "issue" for this document/this project.
3. Adding the option to list all ignored issues, to enable users to un-ignore certain issues.

I have no idea how difficult it is to implement this, but I think it would add value, which is why I (completely arbitrary and probably wildly inappropriately) gave this RFE priority 7. :)