title: What's the meaing of: incremental, preDexLibraries, jumboMode, inside dexOptions?
body: <p>inside build.gradle we can add that params</p>
  
  <pre><code>android {
      dexOptions {
          incremental 
          preDexLibraries
          jumboMode 
          javaMaxHeapSize
      }
  }
  </code></pre>
  
  <p>but documentation is too low</p>
  
  <p><a href="http://google.github.io/android-gradle-dsl/current/com.android.build.gradle.internal.dsl.DexOptions.html#com.android.build.gradle.internal.dsl.DexOptions">http://google.github.io/android-gradle-dsl/current/com.android.build.gradle.internal.dsl.DexOptions.html#com.android.build.gradle.internal.dsl.DexOptions</a></p>
  
  <blockquote>
    <p>boolean incremental</p>
    
    <p>Whether to enable the incremental mode for dx. This has many limitations and may not work. Use carefully.</p>
    
    <p>boolean jumboMode</p>
    
    <p>Enable jumbo mode in dx (--force-jumbo).</p>
    
    <p>boolean preDexLibraries</p>
    
    <p>Whether to pre-dex libraries. This can improve incremental builds, but clean builds may be slower.</p>
  </blockquote>
  
  <p>1) which limitations are in incremental?</p>
  
  <p>2) what is jumbo mode?</p>
  
  <p>3) what is pre-dex libraries?</p>