Upgrade to QGIS v3.x

v2.0.0

Update version number before final release of v2.0.0

Fix for NetworkX upgrade from v1 to v2 (still for QGIS v2.x

Long-awaited fix for NetworkX upgrade from v1 to v2, still for QGIS v2.x

Fix for NetworkX upgrade from v1 to v2
Replace edges_iter with edges
ref: https://networkx.github.io/documentation/stable/release/migration_guide_from_1.x_to_2.0.html

Updated metadata to v1.0.4