Detect target chart type from CSV data

[anthonyserious]

When CSV files are dropped, dropchart.io indiscriminately tries to render the data as a stepped area chart. A facility should be introduced to try to infer the chart type based on the data.

This facility could be extended to infer at different levels:

1. JSON
2. CSV (stepped area chart, pie chart, bubble chart, ...)
3. vmstat (Linux/Solaris/BSD/AIX formats)
4. uptime
   ...