Add node 10 builds

Bump version.

Adds noroute_estimate option

Prepare RC.1

Bump to 5.20.0-alpha.4

Bump to 5.20.0-alpha.3

bump to alpha 2

 - Changes from 5.18.0:

    - Optimizations:
      - CHANGED: Use Grisu2 for serializing floating point numbers. [Project-OSRM#5188](Project-OSRM#5188)
      - ADDED: Node bindings can return pre-rendered JSON buffer. [Project-OSRM#5189](Project-OSRM#5189)
    - Profiles:
      - CHANGED: Bicycle profile now blacklists barriers instead of whitelisting them [Project-OSRM#5076
](Project-OSRM#5076)
      - CHANGED: Foot profile now blacklists barriers instead of whitelisting them [Project-OSRM#5077
](Project-OSRM#5077)
      - CHANGED: Support maxlength and maxweight in car profile [Project-OSRM#5101](Project-OSRM#5101]
    - Bugfixes:
      - FIXED: collapsing of ExitRoundabout instructions [Project-OSRM#5114](Project-OSRM#5114)
    - Misc:
      - CHANGED: Support up to 512 named shared memory regions [Project-OSRM#5185](Project-OSRM#5185)

Prep alpha release for testing.

Changes from 5.18.0:

Optimizations:
	CHANGED: Map matching is now almost twice as fast. Project-OSRM#5060
	CHANGED: Use Grisu2 for serializing floating point numbers. Project-OSRM#5188
	ADDED: Node bindings can return pre-rendered JSON buffer. Project-OSRM#5189
Bugfixes:
	FIXED: collapsing of ExitRoundabout instructions Project-OSRM#5114
Misc:
	CHANGED: Support up to 512 named shared memory regions Project-OSRM#5185