Drop low-value charts

The total users/volume charts provide little value because they can only
ever increase. The charges and withdrawals charts don't tell us much
that the weekly volume chart doesn't, especially after #1383.

www/about/stats.spt

@@ -216,14 +216,6 @@ def out():
     <p>On average, people who tip, tip ${{ "%.2f" % average_tip }} each to
     {{ other_people }}. </p>
 
-    <div class="chart-wrapper">
-        <a name="users"></a>
-        <h2>Total Users</h2>
-        <p class="note">Anyone who's ever created an account on Gratipay</p>
-        <div class="chart" data-chart="total_users"></div>
-        <div class="x-axis">weeks</div>
-    </div>
-
     <div class="chart-wrapper">
         <a name="active"></a>
         <h2>Active Users</h2>
@@ -232,14 +224,6 @@ def out():
         <div class="x-axis">weeks</div>
     </div>
 
-    <div class="chart-wrapper">
-        <a name="cumulative-gifts"></a>
-        <h2>Total Gifts ($)</h2>
-        <p class="note">Money transferred within Gratipay (cumulative)</p>
-        <div class="chart" data-chart="total_gifts"></div>
-        <div class="x-axis">weeks</div>
-    </div>
-
     <div class="chart-wrapper">
         <a name="gifts"></a>
         <h2>Weekly Gifts ($)</h2>
@@ -248,24 +232,6 @@ def out():
         <div class="x-axis">weeks</div>
     </div>
 
-    <div class="chart-wrapper newline">
-        <a name="charges"></a>
-        <h2>Charges ($)</h2>
-        <p class="note">Money moved into Gratipay</p>
-        <div class="chart" data-chart="charges"></div>
-        <div class="x-axis">weeks</div>
-    </div>
-
-    <div class="chart-wrapper">
-        <a name="withdrawals"></a>
-        <h2>Withdrawals ($)</h2>
-
-        <p class="note">Money withdrawn from Gratipay</p>
-
-        <div class="chart" data-chart="withdrawals"></div>
-        <div class="x-axis">weeks</div>
-    </div>
-
     <div class="chart-wrapper">
         <a name="number-by-amount"></a>
         <h2>Number of Tips by Amount</h2>