type fixes & docs

src/public/Terminal.ts

@@ -263,18 +263,18 @@ class UnicodeApi implements IUnicodeHandling {
   constructor(private _core: ITerminal) {}
 
   public register(provider: IUnicodeVersionProvider): void {
-    (this._core as any)._unicodeService.register(provider);
+    this._core.unicodeService.register(provider);
   }
 
   public get versions(): string[] {
-    return (this._core as any)._unicodeService.versions;
+    return this._core.unicodeService.versions;
   }
 
   public get activeVersion(): string {
-    return (this._core as any)._unicodeService.activeVersion;
+    return this._core.unicodeService.activeVersion;
   }
 
   public set activeVersion(version: string) {
-    (this._core as any)._unicodeService.activeVersion = version;
+    this._core.unicodeService.activeVersion = version;
   }
 }