Replaced range classes with a single interval class.
Fixed range extension methods.
Merge remote-tracking branch 'origin/develop' into feature/core

Conflicts:
	src/Georadix.Core.Tests/DateTimeOffsetRangeFixture.cs
	src/Georadix.Core.Tests/DateTimeRangeFixture.cs
	src/Georadix.Core.Tests/DoubleRangeFixture.cs
	src/Georadix.Core.Tests/IntRangeFixture.cs
	src/Georadix.Core.Tests/ShortRangeFixture.cs
Added extension methods for long and float.
Removed value doc tags.
Fixed review comments.
Merge pull request #27 from Georadix/feature/core

Range overhaul