Added context manager module

Added a context manager for handling and managing windows/buffers
constructed by built-ins. This was handled by the `new()` function in
presser/init.lua but is now a dedicated module.

presser/context_manager/init.lua

@@ -0,0 +1,45 @@
+local a = vim.api
+local g = vim.g
+
+-- setup a new global context manager for windows/buffers
+g.presser_buf_ctx = g.presser_buf_ctx or {} 
+
+
+local M = {}
+
+local get_ctx_head = function ( ctx )
+  return g.presser_buf_ctx[ctx][1]
+end
+
+M.create = function ( ctx )
+  local c = g.presser_buf_ctx
+  -- create specific context manager if it doesn't exist
+  if not c[ctx] then
+    c[ctx] = {}
+    g.presser_buf_ctx = c
+  end
+end
+
+-- :TODO: restructure function to allow for new data structure (see todo file)
+M.update = function ( ctx, data )
+  local c = g.presser_buf_ctx
+  -- ensure that the context exists
+  if not c[ctx] then
+    M.create( ctx )
+  end
+
+  table.insert(c[ctx], data)
+  g.presser_buf_ctx = c
+end
+
+M.flush = function ()
+  for ctx, ctx_tbl in pairs( g.presser_buf_ctx ) do
+    for _, win_id in pairs( ctx_tbl ) do
+      a.nvim_win_close( win_id, true ) -- buffer contents are irrelevant in this context to save
+    end
+  end
+
+  g.presser_buf_ctx = {} -- clear the global context manager
+end
+
+return M