fix!: get/set env variables via env table (#294)

this removes the old "virtual global table" which allows
getting environment variables via just their names in lua.

this means:
an environment variable (like TERM) would need to be accessed
via the `env` table instead of just using TERM in lua.

`TERM` -> `env.TERM`
they can also be set via `env.VARIABLE = 'value'

nature/env.lua

@@ -0,0 +1,10 @@
+env = {}
+
+setmetatable(env, {
+	__index = function(_, k)
+		return os.getenv(k)
+	end,
+	__newindex = function(_, k, v)
+		os.setenv(k, tostring(v))
+	end
+})

nature/init.lua

@@ -26,6 +26,7 @@ require 'nature.opts'
 require 'nature.vim'
 require 'nature.runner'
 require 'nature.hummingbird'
+require 'nature.env'
 require 'nature.abbr'
 
 local shlvl = tonumber(os.getenv 'SHLVL')
@@ -35,36 +36,6 @@ else
 	os.setenv('SHLVL', '0')
 end
 
-do
-	local virt_G = { }
-
-	setmetatable(_G, {
-		__index = function (_, key)
-			local got_virt = virt_G[key]
-			if got_virt ~= nil then
-				return got_virt
-			end
-
-			if type(key) == 'string' then
-				virt_G[key] = os.getenv(key)
-			end
-			return virt_G[key]
-		end,
-
-		__newindex = function (_, key, value)
-			if type(value) == 'string' then
-				os.setenv(key, value)
-				virt_G[key] = value
-			else
-				if type(virt_G[key]) == 'string' then
-					os.setenv(key, '')
-				end
-				virt_G[key] = value
-			end
-		end,
-	})
-end
-
 do
 	local startSearchPath = hilbish.userDir.data .. '/hilbish/start/?/init.lua;'
 	.. hilbish.userDir.data .. '/hilbish/start/?.lua'