Bounded memory streaming reporters and dumpers

This release makes the reporters and dumpers work in bounded memory over result streams which addresses #132.

Fix DELETE method support in targets

This is a bug fix release that fixes support for the DELETE HTTP method in targets.
Thanks to @shriiitk for reporting #134

Increase precision of quantile estimation

This release fixes #129 which reported that quantile estimation in reports looked wrong for some data sets. The issue was the streaming quantile algorithm used wasn't tuned appropriately. However, after considering the problem for a while, it became clear that using such an algorithm is not necessary since we have all the data ready anyways. Therefore, I implemented R's 8th type of batch quantile estimation which is approximately median-unbiased regardless of the data distribution.

Revert recent timeout behaviour change

A recent change had an unintended effect of considering time to read response bodies in each request deadline. This has been reverted.

Allow case sensitive headers in attacks

This release enables using case sensitive headers in attacks. Thanks to @hi-t-ch for the initial discussion and to @GeertJohan to follow up.

Major performance improvements

This release brings major improvements to vegeta's performance and how much throughput it can generate reliably.

• Major performance improvements that allow much higher attack rates
• Expose connections flag in the attack command
• Add global cpu and heap profiling flags
• Measure actual attack rate and print it in relevant reporters

Thanks to @vdel26 who kicked this off with #120 and to @giltene for inspiration with his previous feedback and work on https://github.com/giltene/wrk2.

Plot reporter improvements

• Update dygraph to latest version
• Improve plot reporter screenshot rendering by using html2canvas.js
• Improve plot reporter performance

Thanks to @nathany for reporting: #119

Allow spaces in report histogram flag format

This release allows spaces in the report command hist reporter flag format. This means that passing hist[0,5ms] and hist[0, 5ms] to the -reporter flag of the report command is equivalent.

Version flag, default dumper and regression fix

This release adds a --version flag to the vegeta command, sets the default dumper as json so you don't have to type the extra flag for the common use case and fixes a regression introduced by the previous release.

Bug fix

This release fixes a bug that incorrectly counted the number of bytes received in response bodies.
Thanks to @pwaller for reporting it in #113.