Merge Multi column sorting into current Materal#2

Merged

FirstVertex merged 9 commits intoFirstVertex:masterfrom

relair:multi-column-sorting

Feb 8, 2019

Commits on Oct 10, 2018

feat(sort): allowing sorting by multiple columns
Marcin
committed

Commits on Oct 11, 2018

Commits on Oct 17, 2018

Merge branch 'master' of https://github.com/relair/material2 into multi-column-sorting
Marcin
committed

Commits on Oct 30, 2018

feat(sort): allowing sorting by multiple columns
Marcin
committed
Merge branch 'master' of https://github.com/relair/material2 into multi-column-sorting
Marcin
committed
fix(sort) removing unused imports for multi-sort-header spec
Marcin
committed

Commits on Oct 31, 2018

feat(sort): Changing comments for SortHeaderStrategy and spiting error for multi-sort
Marcin
committed

Commits on Dec 4, 2018

Merge branch 'master' of https://github.com/relair/material2 into multi-column-sorting
Marcin
committed