initial commit of twitter mention with history.  A history object
has been added to keep track of the searching.  This save preserves the
initial functionality before adding a Vega-based visualization.
Saving twitter mention history because vega history rendering is starting to work.  This needs the auto-scaling trick I used in the tableVis (NCI) app so values can wander over time and not mess up the vis.  It needs to autoscale.
commit the Vega spec, too.  This bar graph is not dynamically scaled, but it works.
save working spec before adding auto-scaling to the visualization
modified index.html to reference local vega-1.3.3 to reduce startup time and be cache ready.  This app can run without internet access now.  Text labels for history bars are invisible unless hovered over (they are right above the bar top).  This save preserves functionality before trying to re-arrange as a group so hover over center of bar turns on the name.
Added function where graph auto-scales and has text labels.  hover of labels (just above bar) draws only.  Click of label re-centers the graph around the clicked entity. About to re-arrange the page to put the history chart(s) to the right of the mention graph.
Moved tweet history to the right of the screen.  I needed to add a title above the vega chart before it sized correctly in bootstrap.  Must be vega doesn't know a size during the layout phase.  After using it, I notice that I would like to dynamically resize the window.
The initial version of sending and receiving tweet charts are working!
converted from in-memory history to mongodb-based history mechanism.  Reproduced same results as in-memory.  Now ready for adding sorting() and smart limits, etc. to history record returns. Also could separate the history out into a different service, as needed, to send control commands to history service.
implemented sort and limit in mongo history class return.
Added pop-up with controls for controlling history.  History display can be adjusted and length of displayed history can be changed.  Minor cleanup of the interface.
stable version, except center-on-click appears to work only once.  saved stable version before experimenting with addition of zoom / pan in the tweet graph element.
save before exploring cousin for Vega spec
changes to make the app ready for the first year2 dataset (South America)
Merge /Users/clisle/Projects/xdata/code/github/xdata-apps/twitter-mention-history

Conflicts:
	twitter.js