aql: basic tab-completion using readline

please review before merging

added 10 commits

• 71cafeb6...16cd0cfe - 9 commits from branch master
• 8ca151ee - aql: basic tab-completion using readline

Compare with previous version

added 6 commits

• cce69eae - go around global variable
• 46b1b5d2 - enclose readline prompt completion in a class
• eaf677e0 - takeout history handling from Prompt
• ca52bbf5 - push add_history to readline history handler class
• 043809bb - make readline registration standalone
• b98b3eed - add getHistoryFile getter

Compare with previous version

enabled an automatic merge when the pipeline for b98b3eed succeeds

added 4 commits

• 8f90f0f4 - takeout history handling from Prompt
• 29b93a6c - push add_history to readline history handler class
• 973a3feb - make readline registration standalone
• da69f7c4 - add getHistoryFile getter

Compare with previous version

enabled an automatic merge when the pipeline for da69f7c4 succeeds

added 4 commits

• d31ab146 - takeout history handling from Prompt
• cc23d266 - push add_history to readline history handler class
• c2032adb - make readline registration standalone
• 6ac0671c - add getHistoryFile getter

Compare with previous version

enabled an automatic merge when the pipeline for 6ac0671c succeeds

merged