Improve Autocomplete Functionality

[keanerobinson]

Issue Summary

• This issue occurs on Chrome on High Sierra 10.13.3
• I can't currently make use of the predictive dropdown options in the query editor. The dropdown options need to fully replace the line being typed (I'll reproduce the steps in the following section to elaborate).

Steps to Reproduce

1. Typing in a table name

• I'd like to use one of the dropdown options to speed up the time it takes to write my query
• Let's assume that I want to select the first option in the dropdown and that I either hit enter or click on the option

2. Result after hitting enter / clicking

• Obviously this is not a valid table name as there's a double reference to the schema
• The dropdown works fine when typing in field/table names when there is no join involved but the autocomplete results don't work when a . has been typed because only the text which follows the . gets replaced.