System information (version)

• OpenCV => 3.4 and onward
• Operating System / Platform => all supported
• Compiler => N/A

Detailed description

I have extended summary.py to support tab separated columns, a feature I find very useful for loading the data of the summary into spreadsheets.

The commit is at fpetrogalli@1e7ea95

A PR is on the way.

Please let me know if this is OK for OpenCV to have.