Don't select completions until tab has been pressed

Before, pressing <Enter> when completions were visible would execute the
selected completion. As soon as completions were provided, the first
item would be selected. This could cause issues e.g. when changing
folders:

  :cf <Enter>

Previously, this would have selected the first folder in the list. Now,
since <Tab>, <C-n>, etc have not been pressed to select the first
completion, the command above simply executes `:cf `.

To accomplish this, a "no-op completion" has been added at index -1.

0 files changed, 0 insertions, 0 deletions