MD: MD 2 Point Addition

[Markkos1992]

A point should be added at Friendship Rd due to its connection to MD 261.  I see no evidence officially that MD 261 should be extended to MD 2.

Otherwise it may be a good idea down the road to relabel the US 50 points along its freeway portion west of the US 301 split (also affecting US 301 and MD 2).  I-595 has them along its portion.

[Duke87]

FriRd point added to MD2.

As for the exit numbers, the manual sayeth:

If the highway is a freeway and has a unique exit numbering system based on its own designation without the exit numbers restarting, use the exit numbers as waypoint labels.

This of course leaves open for interpretation what exactly is meant by "the highway is a freeway". A significant length of US 50 in Maryland (where the exit numbers are) is freeway, but the whole route is not.

Established precedent in this sort of circumstance seems to be that using exit numbers is permissible, but not required.

In spite of the lack of requirement, though, it was bugging me, so I went ahead and put the exit numbers in for US50.
US301 and MD 2 get them indirectly as concurrent routes, e.g. "US50(21)".

https://github.com/TravelMapping/HighwayData/pull/3372

[Markkos1992]

Just to note, I brought up the exit numbers as part of the conversation in the below thread on US 264.  I definitely think it is the right move here just because of the length of the freeway.

http://forum.travelmapping.net/index.php?topic=3297.msg16534#msg16534