refactor(all): better interfaces, add router event export, more tests

[bigopon]

No description provided.

[bigopon]

This is now ready for review.

• refactor to TS
• ensure compat with latest release
• add export RouterEvent for better typings/hooks
• include fix Updating from version 1.5.0 to ^1.6.0 breaks route redirect to child route #619
• add more unit & integration tests

[bigopon]

For comparison, typings is based on 1.5.0 release (same for 1.6) at https://github.com/aurelia/router/blob/2a8a16622dc162c9bd24028a76420692f2a0882a/dist/aurelia-router.d.ts

[bigopon]

The latest commits https://github.com/aurelia/router/pull/632/files/26facc5f83fd7bb48da8e5015efb943e913c21f7..7d3ee63e77d585f7964ea6706163e1cd2dff7691 will export a few critical information related to router event enum and pipeline slot name enum, along with some comments for better understanding & usage

[EisenbergEffect]

@bigopon Is this ready?

[bigopon]

@EisenbergEffect yes it is ready. Everything has been reverted to internak refactoring instead of aiming for a 2.0 beta. Its a big refactoring so if needed, we can do a RC release

[EisenbergEffect]

@bigopon What is the release process for this library now? Just build and release from master? After this next release, will we be able to use the develop branch and align this process with the other updated repos?