Feature: Textboxes and other text-related features (#90)

* Textboxes: setup prefab

* Textboxes: basic functionality finished

* Textbox: scaling

* Textbox: open captions

* Textbox: res edits

* Textbox: song artist

* Textbox: closed captions

* Textbox: fix not being able to use multiple text events

* I/O: save / load remixes using UTF-8 encoding

* Textboxes: stop editor shortcuts while typing

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+            #pragma multi_compile __ UNITY_UI_CLIP_RECT
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+ 
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+            float _Smoothness;
+            float _OutThickness;
+            float _OutSmoothness;
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+            v2f vert(appdata_t v)
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+                #endif
+ 
+                #ifdef UNITY_UI_ALPHACLIP
+                clip (color.a - 0.001);
+                #endif
+ 
+                return color;
+            }
+        ENDCG
+        }
+    }
+}

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