remove deprecation warnings in XCode 8.3

[LeviDahl]

Remove deprecations related to M_PI, M_PI_2, DBL_MAX, and DBL_EPSILON, which are deprecated in Swift 3.0.

[codecov-io]

Codecov Report

Merging #2162 into xcode-8.3 will increase coverage by 0.14%.
The diff coverage is 47.22%.

@@              Coverage Diff              @@
##           xcode-8.3    #2162      +/-   ##
=============================================
+ Coverage      18.39%   18.54%   +0.14%     
=============================================
  Files            124      124              
  Lines          14305    14194     -111     
=============================================
  Hits            2632     2632              
+ Misses         11673    11562     -111

Impacted Files	Coverage Δ
Source/Charts/Animation/ChartAnimationEasing.swift	0% <ø> (ø)	✅
...Data/Implementations/Standard/ChartDataEntry.swift	7.4% <ø> (ø)	✅
Source/Charts/Highlight/RadarHighlighter.swift	0% <ø> (ø)	✅
Source/Charts/Renderers/PieChartRenderer.swift	0% <ø> (ø)	✅
...a/Implementations/Standard/CombinedChartData.swift	0% <ø> (ø)	✅
.../Implementations/Standard/ChartDataEntryBase.swift	8.16% <ø> (ø)	✅
...arts/Data/Implementations/Standard/ChartData.swift	30.5% <100%> (ø)	✅
Source/Charts/Utils/ChartUtils.swift	34.84% <100%> (ø)	✅
...s/Data/Implementations/Standard/ChartDataSet.swift	33.44% <66.66%> (ø)	✅
Source/Charts/Charts/PieRadarChartViewBase.swift	0% <ø> (ø)	✅
... and 2 more

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[liuxuan30]

.greatestFiniteMagnitude this name is killing me.

[danielgindi]

"This value corresponds to type-specific C macros such as FLT_MAX and DBL_MAX. The naming of those macros is slightly misleading, because infinity is greater than this value."

So the old naming is slightly misleading....