Unimplemented DMF control attributes

[ike709]

See http://www.byond.com/docs/ref/skinparams.html#allparamstable

• [x] is-checked (#1462)
• [x] can-check (#1462)
• [x] group (#1462)
• [ ] is-transparent
• [ ] drop-zone
• [x] title
• [ ] titlebar
• [ ] can-close
• [ ] can-minimize
• [ ] can-resize
• [ ] is-maximized
• [ ] image
• [ ] image-mode
• [ ] stretch
• [ ] keep-aspect
• [ ] transparent-color
• [ ] alpha
• [x] splitter (#1408)
• [ ] multi-line
• [ ] is-flat
• [ ] pushbutton
• [ ] icon-size
• [ ] text-mode
• [x] on-show (#1450)
• [x] on-hide (#1450)
• [ ] link-color
• [ ] visited-color
• [ ] cell-span
• [ ] style
• [ ] enable-http-images
• [ ] focus
• [ ] max-lines
• [ ] flash
• [ ] no-command
• [ ] map-to
• [ ] show-history
• [ ] tab-background-color
• [ ] tab-font-family
• [ ] tab-font-size
• [ ] tab-font-style
• [ ] tab-text-color
• [ ] tabs
• [ ] show-url
• [ ] use-title
• [ ] highlight-color
• [ ] allow-html

[wixoaGit]

All possible control parameters were added as valid keywords in 6a03889def6fc42058c4aa4d817e3649bdfde16c. They currently don't do anything, and instead just print warnings to the console.

[amylizzle]

1462 does is-checked, can-check, group

1450 does on-show and on-hide

[amylizzle]

1757 defines all the properties and their defaults but does not implement behaviour