renamed module name
renamed from multi_node_trace.
renamed to percept2_multi_node_trace.
moved a couple of functions to percept.erl
return to 'dot to svg' command the operation fails; added the directory for storing svg files generated as a parameter to some functions.
more checking added to the generation of svg files.
make the path to svg files as a parameter of svg file generation functions.
refactored the process tree generation.
let user decide a directory for temporary files if Percept cannot.
changed the type of information to avoid type errors.