Add vim like text object selection bindings like ci(, ya", etc..
Copied from softmoth/zsh-vim-mode. Since all the other interesting parts
are already covered (for example by p10k) in my config, sourcing the
entire plugin would not make sense.
Replace all occurrences of [ with [[ in bash and zsh scripts and
configs.
Performance wise it makes sense to use the builtin instead of calling an
external command also when from a functionality stand point `test` would
suffice.
Replace the zsh-history-substring-search plugin with fzf by adding a
function that starts the fzf-history-widget when pressing <Up> with a
nonempty BUFFER. The widget then uses the buffer automatically as query
for fzf.
