Support piping long log lines from the function

[LucasRoesler]

Description

• Use the bufio ReadLine method so that we can check if the the log line has been broken into several parts due to the internal buffering. This implementation has been adapted from https://github.com/hashicorp/go-plugin/pull/98

  The implementation also preserves the timestamp prefix and is fully backwards compatible.

Motivation and Context

• [x] I have raised an issue to propose this change (required)

Resolves #100

How Has This Been Tested?

A new unit test has been added

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I've read the CONTRIBUTION guide
• [x] I have signed-off my commits with git commit -s
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[alexellis]

Whilst I think this patch should be merged, it does also add a lot of complexity and maintenance overhead.

Would making the total buffer size configurable per function (retaining the default) also fix the issue?

[LucasRoesler]

Whilst I think this patch should be merged, it does also add a lot of complexity and maintenance overhead.

Would making the total buffer size configurable per function (retaining the default) also fix the issue?

Most of the complexity in this change comes from the fact that of-watchdog uses log instead of just printing to stdout, if we are willing to make a breaking change, we can simplify this a lot.

I don't think just configuring the buffer size is going to be a great dev experience because what would otherwise be a successful function request could instead completely crash an instance without much warning just because of logging. Making it configurable means it could be resolved for each case, but we will continue to see questions about it (even if we document it)