feature: new params for graphviz + solves #70

[maciejczyzewski]

Changes:

• solve abs path bug Pyan crashes when i give filename or don't give  #70

• new params for graphviz (--dot-ranksep 5 -> ranksep; --graphviz-layout fdp -> layout)
  when working with --html and someone wants more space or zoom capacity, ranksep is helpful

• tested layout param on various projects: dot (default); fdp (square graph);
  but every layout that is documented in: https://graphviz.org/documentation/#layout-manual-pages works.

• updated .gitignore (files gen. after visualize_pyan_architecture.sh)

Example (--graphviz-layout fdp):

[Technologicat]

Looks good to me.

@jdb78 : anything to add?

[jdb78]

@maciejczyzewski Could you give your consent to relicense your contributions under the MIT and BSD licences here: #68?

And: I think the readme changes for you to pyan3. I think we install pyan. Otherwise all good with me :)

[maciejczyzewski]

Yeah, sure 😄 (already commented in #68)

I switched to pyan3 in readme since pip install pyan3 did not install the pyancommand on my machine as it should have.

Edit:
Should there be an additional line "pyan = pyan.main:main" here in https://github.com/Technologicat/pyan/blob/master/setup.py#L130

[lofidevops]

@Technologicat @jdb78 FWIW I have used this branch successfully on a moderately complex project, and it works as expected.