Header search, re-add breadcrumbs, other small features

[vincerubinetti]

Closes #266
Closes #227
Closes #77
Closes #80

Summary of changes (for reviewers, going commit by commit is better for this PR):

• rework 404 redirect
• add "BETA" to prod banner
• update category icons
• change css data attr selectors to class selectors
• show taxon info in node badge for genes
• in node badge, remove link option. instead, show link unless already on page being linked to (current node).
• rework and reinsert breadcrumbs, but only hook up to hierarchy
• refactor predicate badge
• dont automatically change case of labels in select components, do that from parent using it
• in multi select component, solo-select first option clicked
• add icon support to multi select component
• in select components, fix hover then enter press bug
• tweak table component styling, save expanded state to local storage
• fix tab component keyboard wrapping behavior
• add search box to header and change styles to accommodate
• tweak homepage nexus visualization
• on testbed, show all custom icons
• change tab search higher-order-component to accommodate search box in header
• re-add breadcrumbs section
• add "back to search" button at top of node page

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