Update VRP links in instance provider

[abeham]

The links for "Cordeau (MDCVRPTW)", "Homberger (CVRPTW)", and "LiLim (PDPTW)" need to be updated. Please also update the VRP reference wikipage.

[pfleck]

r11280 Broken URLs updated

[abeham]

r11282: added reference publication and updated URL of Cordeau instance provider

Please check: There are MDCVRP and MDCVRPTW instances in the Cordeau data set. We do not separate those and treat them all as MDCVRPTW. If the MDCVRP is available in our implementation we should split the instances: ".vrp" are MDCVRP and "_tw.vrp" are MDCVRPTW.

[pfleck]

r11292 Split the CordeauInstanceProvider into 2 InstanceProvider which separates the MDCVRP and MDCVRPTW instances.

[abeham]

Rename CordeauInstanceProvider to CordeauMDInstanceProvider and the other to CordeauMDTWInstanceProvider.

Add the best-known solution files to the Cordeau instances so that we also load these and set the BestKnownSolution and BestKnownQuality parameters. I saw that this was only implemented for the Augerat and Taillard libraries so far.

[pfleck]

r11294 Renamed CordeauInstanceProvider to CordeauMDInstanceProvider and CordeauTWInstanceProvider to CordeauMDTWInstanceProvider as suggested by abeham.

[pfleck]

r11295

• Fixed VRPInstanceProvider parsing of best known solutions. If a file contains multiple solutions (Augerat A-n45-k7), only the first solution is used.
• Fixed broken .opt files (R in Route missing): B-n57-k9, E-n76-k7, tai75a

[pfleck]

r11296 Renamed Cordeau instance files according to their instance provider class.

[pfleck]

Integrating of the best known solutions for multi-depot is not yet possible. The .opt format does not store the vehicle assignments to a route and therefore the solution is ambiguous for multi-depot variants.

This feature will be addressed in #2229.

[abeham]

I updated the links at the reference page, I think you can release the changes.

[pfleck]

r11334 Merged r11280, r11282, r11292, r11294, r11295 and r11296 into stable.