jq 1.6 has a poor performance

[diafour]

Related issue: jqlang/jq#2069

There was a migration to the tag "1.6" in jq sources because of crashes: #6. But 1.6 has poor performance. So the plan is:

• create a benchmark to check if libjq-go is affected
• choose a commit in master branch that has a good performance and don't crash on subsequent calls

Also, a 1.5 branch can be created with jq sources from tag "1.5".

[diafour]

Apart from the poor performance there is a problem with sequential Run calls. If jq expression has fromjson or tonumber that fail, then subsequent calls to jq_compile will fail and segfaulted.

The last commit that works well is jqlang/jq@b6be13d. Also, this commit has good performance. So stick to this one: #11

[diafour]

Can be closed as resolved:

• No issues with jq performance in shell-operator since v1.0.0-beta.9 release.
• README now contains information regarding choosing a jq commit.