Draft: Add single quotes and quote escaping to command parser

this patch adds two convenience features to the command parser:

• parameters can be wrapped in single quotes
• quotes can be escaped with backslash

these two features solves a minor issue with command parameters where double quotes can't easily be escaped. with this patch, you now have two options: either wrap it in single quotes (say 'i can say "quotes" here'), or escape it with a backslash (say "i can say \"quotes\" here")

EDIT: single quotes was removed due to concerns of breaking changes (thanks @Zwip-Zwap_Zapony for pointing that out).