title: MP Android Chart, custom xAxis labels only on entries
body: <p><em><strong>1)</strong></em> I'm practicing stuff with graphs in order to add that feture to my app, I want the upper labels ( the xAxis base ) to be shown only where entries occur.</p>
  <p>I haven't found a suitable solution online yet, and currently it appears on every xAxis from first entry to last entry as in the picture below:</p>
  <p><a href="https://i.stack.imgur.com/QOFzu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QOFzu.png" alt="enter image description here" /></a></p>
  <p>I want it to be without the one sI deleted, as shown in the picture below:</p>
  <p><a href="https://i.stack.imgur.com/USOPN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/USOPN.png" alt="enter image description here" /></a></p>
  <p><em><strong>2)</strong></em> and the second question I'm struggling with it is that I want to be able to draw for example in (x=5, y=7) and after it to draw at (x=1, y =3), but it wont let me add an entry with a smaller x that any other entry that already in the graph.</p>