Fix some pylint errors/warnings
Fix some pylint errors/warnings

Remaining errors:

************* Module neurom.view.common
W:120,14: Unused argument 'fig' (unused-argument)
R:184, 0: Too many local variables (43/15) (too-many-locals)
R:184, 0: Too many branches (17/12) (too-many-branches)
R:184, 0: Too many statements (80/50) (too-many-statements)

Change-Id: I13d27058e194d2662f33cbaa20fd0d4fe4393ac9

wizmer/NeuroM,lidakanari/NeuroM,BlueBrain/NeuroM,eleftherioszisis/NeuroM,mgeplf/NeuroM,liesbethvanherpe/NeuroM,juanchopanza/NeuroM