[Eric] Errors in the 'logparser' tutorial for eric4

[Jaime Seuma]

Hi there.

I've made some minor changes in the tutorial on eric4 I wrote
(http://eric-ide.python-projects.org/eric-tutorials.html), mainly based
on the comments Bradley Wickizer made (thank you, Bradley) about it, as
he went into some trouble following it along.

There is not any new stuff, just some clarifications to make it
(hopefully) clearer.
And also there was a small bug in the source code, that has also been
corrected.

If anyone happens to find something else that could be improved, or any
doubt or anything, plz let me know.

Cheers.

Jaime