Refactored MageRun plugin; added frontname route checking for unknown modules.

[rhoerr]

Per #11 (comment) and #20 (comment): Checking frontnames against those on installed modules would be useful in cases where we don't know what module a given frontname actually corresponds to. This will let us add suspicious routes from probes (#8, #20), and detect on those routes, without knowing further information on the modules in advance. In many cases the modules in question will be significantly out of date or used on a relatively small number of stores. It may also help with data collection by encouraging anyone running them to get in touch.

The original magerun script was pretty small and clean, but adding this code made it the opposite of small and clean, so I significantly refactored it in the process.

The previous module check is now contained within checkIsInstalledModule(), and the new check is within checkIsInstalledRoute().

The route check will run only for modules that are not directly known.

It uses the existing 'Relevant URI' data; no further normalizing needed. It does assume that the frontname is the first element, with or without a leading slash. It ignores anything after. It would be theoretically possible to check for a full controller/action match when the data is available, but that would be much more involved and also much more likely to produce false negatives.

There is a risk of false positives, especially for certain common keywords (EG ajax, vendor). This is unavoidable. In the event of a route match, I have it output:

Matched by route: This may be a false positive where your installed module
shares it with a vulnerable module, but it should be investigated further.
Please contribute info about the module to MageVulnDb if it is relevant.

I did not make any changes to the standalone execution script. Adding the same feature there would easily quadruple its size.

Also have not made any changes to the readme. I don't think any are necessary.

[gwillem]

Great work! I'm hoping @mpchadwick wants to do the code review, my PHP skills are lousy.

[mpchadwick]

A few comments, but mostly LGTM.