Add multi-threaded parsing

[in0finite]

Benchmark (6 cores):

Method	Job	Arguments	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
ParseDemo	Job-PEXGNK	/p:Baseline=true	1,486.5 ms	6.50 ms	6.08 ms	1.00	0.00	26000.0000	1000.0000	-	489.9 MB	1.00
ParseDemo	Job-MQEQFA	Default	1,485.7 ms	6.48 ms	6.06 ms	1.00	0.00	26000.0000	1000.0000	-	489.9 MB	1.00
ParseDemoMT	Job-PEXGNK	/p:Baseline=true	NA	NA	NA	?	?	NA	NA	NA	NA	?
ParseDemoMT	Job-MQEQFA	Default	447.2 ms	23.40 ms	21.89 ms	?	?	34000.0000	11000.0000	1000.0000	582.88 MB	?

[saul]

Many thanks for this! I've built on this as part of #52 - simplifying the API and integrating all of the integration tests.

It's still WIP as there are a couple of bugs that need resolving, but this is a great improvement to performance. Thanks again

[in0finite]

Alright.

Btw, it seems that your implementation is slightly slower (540 ms compared to 450 ms), even if Mac has higher CPU count. Will test it when you merge, to verify.