Loose belts during calibration

I’ve updated the pull request to merge the changes here into the calibration simulator. Overall it seems like it’s working really well, but one bit of strange behavior that I’m seeing is that at the end of converging the result seems to start to oscillate which is a bit concerning:

GIFMaker_me(3)

Edit: This result is with data var measurements = [{bl:1805.88, br:1794.81, tr:1799.43, tl:1799.21},{bl:1742.67, br:1729.06, tr:1867.51, tl:1867.38},{bl:1549.52, br:1929.60, tr:2055.74, tl:1692.36},{bl:1620.86, br:1990.97, tr:1994.95, tl:1614.83},{bl:1698.86, br:2051.95, tr:1937.04, tl:1542.45},{bl:1875.45, br:1863.81, tr:1735.10, tl:1733.83},{bl:2063.84, br:1687.06, tr:1542.02, tl:1935.67},{bl:2002.37, br:1609.47, tr:1613.31, tl:1992.56},{bl:1944.52, br:1536.92, tr:1691.54, tl:2055.14},{bl:1892.13, br:1465.85, tr:1774.07, tl:2127.40},{bl:1683.87, br:1668.33, tr:1943.22, tl:1947.59},{bl:1483.11, br:1874.46, tr:2125.07, tl:1778.54},{bl:1293.29, br:2086.40, tr:2314.98, tl:1625.56},{bl:1369.49, br:2133.37, tr:2253.70, tl:1535.45},{bl:1451.10, br:2185.75, tr:2196.19, tl:1449.29},{bl:1535.14, br:2242.88, tr:2143.58, tl:1367.70},{bl:1626.79, br:2304.56, tr:2095.99, tl:1291.44},{bl:1778.81, br:2115.50, tr:1882.86, tl:1481.08},{bl:1951.07, br:1934.29, tr:1675.00, tl:1681.48},{bl:2132.74, br:1765.35, tr:1474.94, tl:1886.73},{bl:2323.11, br:1612.43, tr:1286.07, tl:2101.44},{bl:2262.45, br:1522.29, tr:1364.73, tl:2145.13},{bl:2205.26, br:1435.94, tr:1446.49, tl:2195.94},{bl:2152.85, br:1354.09, tr:1531.26, tl:2254.54},{bl:2105.64, br:1277.80, tr:1621.77, tl:2315.70},{bl:2064.02, br:1208.86, tr:1711.01, tl:2382.42},{bl:1845.61, br:1410.02, tr:1858.19, tl:2199.83},{bl:1631.47, br:1616.67, tr:2019.26, tl:2025.07},{bl:1423.24, br:1829.38, tr:2196.79, tl:1863.25},{bl:1224.30, br:2045.86, tr:2381.44, tl:1717.86},{bl:1039.61, br:2263.16, tr:2572.74, tl:1593.70},{bl:1120.59, br:2299.57, tr:2514.42, tl:1492.59},{bl:1207.11, br:2343.20, tr:2457.31, tl:1394.06},{bl:1298.07, br:2390.20, tr:2404.60, tl:1298.60},{bl:1393.28, br:2443.73, tr:2356.49, tl:1206.77},{bl:1490.88, br:2500.56, tr:2313.30, tl:1119.70},{bl:1593.60, br:2563.92, tr:2275.30, tl:1038.21},{bl:1717.64, br:2373.39, tr:2054.27, tl:1225.46},{bl:1864.91, br:2188.47, tr:1836.25, tl:1422.45},{bl:2027.54, br:2013.64, tr:1622.64, tl:1628.86},{bl:2204.15, br:1851.88, tr:1415.16, tl:1841.11},{bl:2389.71, br:1706.56, tr:1217.18, tl:2058.23},{bl:2579.98, br:1582.57, tr:1033.90, tl:2274.34},{bl:2522.70, br:1481.42, tr:1115.83, tl:2309.31},{bl:2466.00, br:1382.63, tr:1202.87, tl:2353.65},{bl:2413.65, br:1286.91, tr:1292.60, tl:2401.45},{bl:2365.88, br:1195.00, tr:1385.82, tl:2454.53},{bl:2322.96, br:1107.63, tr:1484.64, tl:2512.13},{bl:2285.22, br:1026.00, tr:1585.05, tl:2574.39},];