Improve performance of Include and Exclude functions

[stuartcarnie]

• given values slices are already sorted, use a binary search to find range
• use copy builtin, which uses highly optimized assembly
• added associated tests for IntegerValues to verify correctness

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Benchmark of Include function

benchmark                                            old ns/op     new ns/op     delta
BenchmarkIntegerValues_IncludeNone_1000-8            651           6.69          -98.97%
BenchmarkIntegerValues_IncludeMiddleHalf_1000-8      1131          114           -89.92%
BenchmarkIntegerValues_IncludeFirst_1000-8           638           33.9          -94.69%
BenchmarkIntegerValues_IncludeLast_1000-8            1269          32.2          -97.46%
BenchmarkIntegerValues_IncludeNone_10000-8           7751          6.76          -99.91%
BenchmarkIntegerValues_IncludeMiddleHalf_10000-8     11582         1378          -88.10%
BenchmarkIntegerValues_IncludeFirst_10000-8          7911          43.8          -99.45%
BenchmarkIntegerValues_IncludeLast_10000-8           12442         38.4          -99.69%

Benchmark of Exclude function

benchmark                                            old ns/op     new ns/op     delta
BenchmarkIntegerValues_ExcludeNone_1000-8            1285          7.34          -99.43%
BenchmarkIntegerValues_ExcludeMiddleHalf_1000-8      1258          148           -88.24%
BenchmarkIntegerValues_ExcludeFirst_1000-8           1268          7.51          -99.41%
BenchmarkIntegerValues_ExcludeLast_1000-8            1125          27.7          -97.54%
BenchmarkIntegerValues_ExcludeNone_10000-8           12665         7.31          -99.94%
BenchmarkIntegerValues_ExcludeMiddleHalf_10000-8     12039         976           -91.89%
BenchmarkIntegerValues_ExcludeFirst_10000-8          12663         7.29          -99.94%
BenchmarkIntegerValues_ExcludeLast_10000-8           10990         34.9          -99.68%

Required for all non-trivial PRs

• Rebased/mergable
• Tests pass
• CHANGELOG.md updated

[jwilder]

Nice speedup!