react-measured-grid displays a virtualized grid
with dynamically measured rows and columns in a scrollable viewing window.
The package provides three commonly used classes:
MeasuredGrid is a React component and is the lead class of the package.
ScrollPosition is a helper class that specifies a positioning of the
grid within the view window.
PositionTracker is a helper class than tracks
measured sizes and various estimates of sizes of rows,
and with modest efficiency provides estimates of the
offset of a row within the entire grid.