Immovable types can be already wrapped into `Maybe`, which can be constructed as default `nullptr`, set to a constructed value via `.emplace()`, but couldn't be cleared back to `nullptr`. The previous commit fixed the bug, this commit adds a test.

Previously we depended on the compiler to implicitly invoke the copy constructor followed by the assignment operator, but this can lead to the compiler making surprising decisions in some cases, such as deciding that the literal 0 is a better match for nullptr than for T. Overloading operator=() to match every copy constructor is the safe thing to do.

Fix minor typo spotted by lintian

Fix JSON field handlers not triggering on union members of annotated types.

Wrap KJ_LOG in braces

Add a way to set a maximum number of event loop turns before we poll for input.

Implement kj::newTee()

Using "for" statement instead of "if", as suggested by Kenton, still
avoids "dangling else" warnings and also allows to have diagnostics on
missing ";" at the end. So this way is better.

Make it possible to configure HttpClient to not reuse connections at all.

This fixes "dangling else" warnings when KJ_LOG is used after unbraced if statement.

Fix json-test on MSVC.

Fix tls-test for OpenSSL 1.1.1.

These errors apparently don't show up until the first read with 1.1.1, and may have different messages.

Apparently this landed on my Debian machine *today* and then all of the sudden the test was failing. I was so confused.

Resolve or defer all TODO(soon)s

Fix Android build/test issues.

More 0.7 fixes

Removed mgravell C# implementation from list

Two fixes for build failure on Android (resubmit)

Have not found a universal way to detect C11 and after some deliberation
__BIONIC__ seems to be a better choice for these cases.

Fix build error because DTTOIF function is not available.