Update external completions
Update external history-substring-search
Update external syntax-highlighting
Bump minimum supported Zsh to v4.3.11

zsh-syntax-highlighting requires this version.

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
[Fix #630] Zsh v4.3.17 is the minimum required
Prezto only enables the main syntax highlighter

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Ensure dircolors uses sh syntax

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Fix typo
Use the `x` command for unrar and rar to preserve paths

unrar and rar will discard everything up to the file name when extracting
with `e`. This breaks extraction of archives that have files with duplicate
file names and ones where the paths are important. The `x` command
extracts with the full path instead.
Don't set node-info if version is 'none'

This is done to make it easier to not show node-info in themes
when no node version is currently in use. This is consistent with
how the Python module's python-info works.

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Fix broken link to 256 color formatting blogpost

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Set default SSH_AGENT_PID for grep

If `SSH_AGENT_PID` is unset, grep will succeed if another ssh-agent is
running as it will match the string `ssh-agent` where the PID was an
empty string. Set a default value for grep to a value that will never
match if unset, i.e. -1.

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Set default GPG_AGENT_PID for grep

If `GPG_AGENT_PID` is unset, grep will succeed if another gpg-agent is
running as it will match the string `gpg-agent` where the PID was an
empty string. Set a default value for grep to a value that will never
match if unset, i.e. -1.