Moved a few functions from vim::api out of unstable feature (#7)

* `nvim_get_current_buf`
* `nvim_get_current_line`
* `nvim_get_current_tabpage`
* `nvim_get_current_win`
* `nvim_list_bufs`
* `nvim_exec`

Author: willothy

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nvim-utils"
-version = "0.1.3"
+version = "0.1.4"
 edition = "2021"
 description = "Utilities for writing neovim plugins in rust"
 authors = ["Will Hopkins <willothyh@gmail.com>"]

README.md

@@ -9,7 +9,7 @@ Using `nvim-utils` is as simple as adding it to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-nvim-utils = "0.1.3"
+nvim-utils = "0.1.4"
 ```
 
 or