Add alias for drush commands

It's a pitty!
'csex' command was our favorite command in the team and it helped us not to die from the depression.

updating the issue summary for all the added commands

I find "ceespex" and "ceespim" easy to say and close enough to the former ones for memorization. Rest then following the pattern:

1. cspex
2. cspim
3. cspac
4. cspde
5. cspso

How about first character from config split and next 2 from command?

1. csex
2. csim
3. csac
4. csde
5. csso

Since
csso: config-split:status-override
is already set
cs-a: config-split:activate (or cs-e for enable)
cs-d: config-split:deactivate
csex: config-split:export
csim: config-split:import

In special csex & csim would be logical (for me), because of alias cex (config:export) & cim (config:import)

It's about removing sex.

+1 on #17
easy to say and quite close to the former ones.

I'm really confused about the length of time that we've been waiting for aliases to be added. Have the first two suggestions in the issue description been added already? I've just been using the full length commands, because I use the command line in VI mode, and searching my shell history is very easy.

For those who want to retain the old ones, isn't there a way to make our own drush aliases? Who is responsible for making the final call/decision here, and why hasn't one already been made (unless the suggestions have already been added, and I'm just not paying close enough attention to the release notes).