Bump Semantic-UI, add more dropdown variations

[mulderr]

Hi,

this is my stab at making dropdown more generic to support simple menus and combos.

Changes:

• bump Semantic-UI to 2.2.13 (unrelated but I don't see why not)
• add uiDropdown'
• add uiDropdownCombo
• add config setting to change dropdown action
• add config setting to change dropdown icon
• add config setting to style dropdown as a button
• add support for these properties: compact, floating, pointing
• update examples

Mostly submitting for feedback at this point.

[mulderr]

No longer need this. Closing. Sorry for the noise.