Get backtrace function names from DWARF sections

Fixes #3926

for NamedTuple

Also allow passing NamedTuple to the corresponding post_form overloads
on HTTP::Client

value is consistent with pointer

Additionally target feels like it's leaking implementation details as
that's the name of the internal instance variable too

This should allow at least pointers to the data section
to work seamlessly with WeakRef and in some cases even
allow stack pointers to be passed, for the crazy

Current implementation of pp returns `nil` always, but `p` returns printed
value. It fixes to return printed value of 'pp'.

Currently `p` (invoke `p` with no argument) shows `{}` because `def p(**objects)` handles it. But in this case it should not display anything and return `nil`.

Spec runner have the option to disable colored output (ANSI codes) when
`--no-color` option is used, example:

    $ crystal spec -- --no-color

However, certain elements in the output didn't fully support that option,
resulting in a mix of non-color and color.

This change unifies that setting and ensures that `--no-color` usage
is fully honored by the output.

Ref #4292

WebSocket: Add support for receiving binary messages

Amend #4075
Fix docs

* Add TTY detection for Colorize
It renames `@on` to `@enabled` because `Colorize::Object` has `#on`
method also, but `@on` is not related and its name does not make a sense.
* Add document comment for Colorize.enabled?
* Allocate TTY to colorize output

Introduces a skip macro method. When called, it stops macro expansion of the rest of the file. This is meant to be used to support Windows (and other target combinations) more cleanly: instead of interleaving code with different targets in the same file through {% if ... %}, diverging code can be kept in different files.

SSLv2 support was removed, some context options were disabled, and
the following symbols were previously macros:

- SSL_CTX_get_options
- SSL_CTX_set_options
- SSL_CTX_clear_options

Fix: OpenSSL 1.1.0