Removes all support (and tests) for the parser category "maintained", as
this is no longer a useful category.
BREAKING CHANGE: replace `ensure_installed='maintained'` by an explicit
list of parsers, or use `'all'` (not recommended).
Unmaintained parsers only give users little benefit but take sometimes a
a long time to install (e.g. Markdown, Julia, Haskell parser). We could
recommend to only install maintained parsers by default.
It will show the current branch at the cursor going the tree as such.
root->node->subnode->leaf
If an argument is provided to `statusline`, then the tree will be
truncated as follows :
..->subnode->subnode
