Better warning in case of error in dot / msc / dia / plantuml image

[albert-github]

The warning messages regarding dot / msc / dia are a bit cryptic and it is hard to find where the file is invoked.
The current messages look like:

Error detected at line 5: Unknown source entity 'fail1'.
Input format error for '.../html/inline_mscgraph_1.msc'
error: Problems generating msc output (error=INPUT FORMAT ERROR). Look for typos in you msc file .../html/inline_mscgraph_1.msc

Error detected at line 5: Unknown source entity 'fail1'.
Input format error for '.../aa.msc'
error: Problems generating msc output (error=INPUT FORMAT ERROR). Look for typos in you msc file .../aa.msc

error: Problems running dot: exit code=1, command='dot', arguments='".../html/inline_dotgraph_1.dot" -Tpng -o ".../html/inline_dotgraph_1.dot.png"'
error: Problems running dot: exit code=1, command='dot', arguments='".../aa.dot" -Tpng -o ".../html/aa.dot.png"'

error: Problems running D:\Programs\dia\0.97.2\bin\dia.exe. Check your installation or look typos in you dia file .../aa.dia

Better it is to have the source file and line in front of it, like most warnings / errors, so it might be easier to locate the problem.

Based on the comment #642 (comment) in #642.

Example: example.tar.gz

[doxygen]

@albert-github Since so many files had conflicts, I decided to redo the changes in a fresh commit. I also added the same for the plantuml files. Please verify if the result is still as expected.

[albert-github]

Indeed between the submitting of the proposed pull request and the integration there have been a lot of changes / refactorings leading to merge conflicts.

At first glance (and also running the test) it looks all OK to me.
One thing that I noticed was that in the original implementation we saw e.g.:

    if (srcLine == -1)
    {
      err("Problems running %s. Check your installation or look typos in your dia file %s\n",
        diaExe.data(),inFile);
    }
    else
    {
      err_full(srcFile,srcLine,"Problems running %s. Check your installation or look typos in your dia file %s\n",
        diaExe.data(),inFile);
    }

which is now replaced with just:

    err_full(srcFile,srcLine,"Problems running %s. Check your installation or look typos in you dia file %s\n",

so in case of unknown source line (should not happen) we will get a warning with the -1 in it but this is not really a problem and maybe even better as now it is better signaled that something is not properly found.