Support case-insensitive autocompletion

[mbierlee]

When completing a symbol defined with capitals, you will only get this symbol as suggestion if the incompletely typed symbol contains capitals. The reverse is also true when trying to complete symbols with lower- or mixed-case.

Symbols should be auto-completable regardless of their actual case and the case of the currently typed characters.

[bruno-medeiros]

Agreed, I'll add this in for the next release