Implement support for multi-letter ligatures.

Typographic ligature: In writing and typography, a ligature occurs where two or more graphemes or letters are joined as a single glyph.
Optimize kerning and advance widths calculation using Paint.getTextWidths(String text, float[] widths);
Make strokeWidth numberProp instead of string.
Fix caching of AlignmentBaseline.
Rename distance to pathLength.
Upgrade gradle build tools.

android/build.gradle

@@ -4,7 +4,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.3.2'
+        classpath 'com.android.tools.build:gradle:2.3.3'
     }
 }