Move canvas-based parsing to Color.ts lib

This removed the allowTransparency code, it didn't actually do much
before, just whether the 'advanced parsing' would allow transparency.
Since we already do the common formats, I'm not even sure what other
format it could be.

src/common/Platform.ts

@@ -13,7 +13,7 @@ interface INavigator {
 // we want this module to live in common.
 declare const navigator: INavigator;
 
-const isNode = (typeof navigator === 'undefined') ? true : false;
+export const isNode = (typeof navigator === 'undefined') ? true : false;
 const userAgent = (isNode) ? 'node' : navigator.userAgent;
 const platform = (isNode) ? 'node' : navigator.platform;