Graph cost setting method improvement

[pedrocamargo]

BEFORE REQUESTING A FEATURE

Purpose of use
Manipulating graph costs and other characteristics is not as straightforward as it seems in two cases:

1. Disconnecting links (setting a_node=b_node) currently requires a rebuild of the graph, as the correlation between compact_graph and the graph is not straightforward
2. Manipulating costs in the graph currently needs to be done in the network and then the graph rebuilt for the change to be propagated to the graph and compact_graph.

Is your feature request related to a problem? Please describe.
The first issue would help criticality analysis implementations, while the second would greatly speed up map-matching implementations where we want to penalize or discount specific links

Describe the solution you'd like
1.1 A method to temporarily disconnect a link
1.2 A method to reconnect the disconnected links
1.3 A method to penalize costs in the graph and compact_graph