Merge branch 'master' of https://github.com/DSpace/dspace-angular into performance-optimizations

config/environment.default.js

resources/i18n/en.json

...browse-by-date-page/browse-by-date-page.component.spec.ts

...-by/+browse-by-date-page/browse-by-date-page.component.ts

...e-by-metadata-page/browse-by-metadata-page.component.html

...y-metadata-page/browse-by-metadata-page.component.spec.ts

...wse-by-metadata-page/browse-by-metadata-page.component.ts

...+browse-by-title-page/browse-by-title-page.component.html

...+browse-by-title-page/browse-by-title-page.component.scss

...owse-by-title-page/browse-by-title-page.component.spec.ts

...y/+browse-by-title-page/browse-by-title-page.component.ts

src/app/+browse-by/browse-by-guard.ts

src/app/+browse-by/browse-by-routing.module.ts

src/app/+browse-by/browse-by.module.ts

src/app/core/browse/browse-entry-search-options.model.ts

src/app/core/browse/browse.service.spec.ts

src/app/core/browse/browse.service.ts

src/app/core/data/browse-items-response-parsing-service.ts

src/app/core/metadata/metadata.service.ts

src/app/core/shared/operators.ts