fix: shortestPathTo https://github.com/scala-graph/scala-graph/issues/12;
fix: method draw;
fix: GraphCanBuildFrom;
mod: edge-equals/hashCode revisited
fix: new line
new: method upsert
fix: 1.7.1 introduced a regression concerning findOutgoingTo/findIncomingFrom
Merge branch 'master' of https://github.com/scala-graph/scala-graph

Conflicts:
	core/src/main/scala/scalax/collection/GraphBase.scala
	core/src/main/scala/scalax/collection/GraphEdge.scala
	core/src/test/scala/scalax/collection/TEdit.scala
	project/Version.scala