v0.5.1: Components update (#88)

• Glyph: Add baseline attribute.
• Material Expansionpanel:
  • Allow programmatic expand and collapse requests even if the panel is
    disabled.
  • Change preserveWhitespace default to false.
  • Add enterAccepts flag.
• Material Input:
  • Show counter regardless of focus.
  • Add error message to MaterialPercentInputDirective.
• Material List: Allow pointer events when disabled.
• Material Popup: Fix positioning when matchMinSourceWidth is true.
• Material Ripple: Show a centered ripple on keypress.
• Material Select:
  • Only display underline when border is also set.
  • Add useCheckMarks to use check marks instead of checkboxes.
• Material Tooltips: Resize to fit contents.
• Material Yes/No Buttons: Add enterAccepts flag.
• Deprecate LazyStreamController and migrate to StreamController.
• Migrate use of LazyEventController to StreamController.
• Documentation fixes.
• Strong mode fixes.