Release of version 3.0.0 - Removing obsolete RangeTree code

Release of version 2.1.0 - Renamed RangeTree to IntervalTree

Release of version 2.0.1 - Bugfixes of copy-paste errors. Thanks to J…

…onas Nyrup.

Release of version 2.0.0.

- Major interface-changes as proposed by Erik Domke.
- Removal of async tree
- Removal of public Rebuild-functionality (will be handled internally)

Preparing release for 1.0.6

Updating release notes and increasing version for newest release

Removing nuspec, building 3 times for netstandard 1.2 (maximum compat…

…ibility), netstandard 2.0 (fewest dependencies pulled into modern application) and classical .net45.

Reverting back to NetStandard 1.2 for maximum compatibility

Adding nuget-specification and link to readme-page.