Provide dot path to plantuml

[wich]

If HAVE_DOT = YES and DOT_PATH is configured, pass the path to the dot executable to plantuml with the -graphvizdot option.

Rationale is that plantuml does not look for dot on the path, but assumes dot is at /usr/bin/dot. The changes allow dot to be in a non-standard location which is configured in the Doxyfile.

[albert-github]

Is it guaranteed that the dotpath has a directory separator as last character (as dot is directly appended to it)?

[wich]

Yes, it is guaranteed that it has a directory separator as last character, this is taken care of in Config::checkAndCorrect in configimpl.l. See also dot.cpp where dot is also directly appended to the config string.