reorganize some stuff

modules/core_lib/ext/string.lua

@@ -0,0 +1,26 @@
+function string:split(sep)
+  local t = { }
+  local function helper(word)
+    table.insert(t, word)
+    return ""
+  end
+  if not self:gsub("%w+", helper):find("%S") then
+    return t
+  end
+end
+
+function string:starts(start)
+  return self:sub(1, #start) == start
+end
+
+function string:trim()
+  return self:match('^%s*(.*%S)') or ''
+end
+
+function toboolean(str)
+  str = str:trim()
+  if str == '1' or str == 'true' then
+    return true
+  end
+  return false
+end