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Fixes #3054

 - TCI Support
 - python 2.7
 - skip build-essential

Remove the call to `ls` that was used to determine the symlink
destination

Reasoning :

* `od` resolves symlink itself due to the use of `fopen`
* Prevent the behaviour of `od` which will hang if the filename is
  empty (i.e. `/sbin/init` missing) as it will be waiting for `stdin`
  compared to quitting with error if the file just doesn't exist

Fixes #3006

Incorporates old Contributing.md with more thorough details on how to contribute, create bug reports, set up the dev environment, and creating PR's itself.

[Docs] added WSL troubleshooting with solution to (6) Could not resolve host: raw.githubusercontent.com

Fixes #2958.

 - xenial can't build node 18
 - bionic can't build node 0.6 or 18

Fixes #2926

On Debian, the default awk/mawk doesn't support the '--version' option;
instead there's mawk-specific '-W version'.

No need to escape the `/` char in a grep pattern.
This is to fix the below error when using newer grep with `nvm_command_info`

> $ nvm_command_info curl
> grep: warning: stray \ before /
> /usr/bin/curl

This happens with at least GNU grep 3.8 version.

Adding function alen(arr) since length(arr) is GNU extension.
Fixes #2916

Fixes #2914

Co-authored-by: epoweripione <siyuwuxin@gmail.com>
Co-authored-by: Jordan Harband <ljharb@gmail.com>

reducing `nvm ls-remote` from almost 20s to below 2s.

Signed-off-by: ryenus <ryenus@gmail.com>