Reorder properties

Move more common properties to the front of property lists,
so that they can be passed as constructor arguments.
E.g.

parser:option "-p" "--port"
   :description "Port number."
   :default "8080"
   :convert(tonumber)

can now be expressed as

parser:option("-p --port", "Port number.", "8080", tonumber)

spec/default_spec.lua

@@ -60,10 +60,7 @@ describe("tests related to default values", function()
 
       it("handles option with default value for multi-argument option correctly", function()
          local parser = Parser()
-         parser:option "-s" "--several" {
-            default = "foo",
-            args = "2-3"
-         }
+         parser:option("-s --several", "Two or three things", "foo", nil, "2-3")
          local args = parser:parse{}
          assert.same({several = {"foo", "foo"}}, args)
       end)

spec/help_spec.lua

@@ -31,9 +31,7 @@ Options:
    end)
 
    it("uses description and epilog", function()
-      local parser = Parser "foo"
-         :description "A description. "
-         :epilog "An epilog. "
+      local parser = Parser("foo", "A description.", "An epilog.")
 
       assert.equal([[
 Usage: foo [-h]
@@ -43,7 +41,7 @@ A description.
 Options:
    -h, --help            Show this help message and exit.
 
-An epilog. ]], parser:get_help())
+An epilog.]], parser:get_help())
    end)
 
    it("creates correct help message for arguments", function()

spec/options_spec.lua

@@ -152,9 +152,7 @@ describe("tests related to options", function()
       describe("Options with optional argument", function()
          it("handles emptiness correctly", function()
             local parser = Parser()
-            parser:option "-p" "--password" {
-               args = "?"
-            }
+            parser:option("-p --password", "Secure password for special security", nil, nil, "?")
             local args = parser:parse({})
             assert.same({}, args)
          end)

src/argparse.lua

@@ -218,13 +218,13 @@ local Argument = new_class({
 }, {
    typechecked("name", "string"),
    typechecked("description", "string"),
-   typechecked("target", "string"),
-   boundaries("args"),
    typechecked("default", "string"),
+   typechecked("convert", "function", "table"),
+   boundaries("args"),
+   typechecked("target", "string"),
    typechecked("defmode", "string"),
    typechecked("show_default", "boolean"),
-   typechecked("argname", "string", "table"),
-   typechecked("convert", "function", "table")
+   typechecked("argname", "string", "table")
 })
 
 local Option = new_class({
@@ -234,15 +234,15 @@ local Option = new_class({
 }, {
    multiname,
    typechecked("description", "string"),
-   typechecked("target", "string"),
+   typechecked("default", "string"),
+   typechecked("convert", "function", "table"),
    boundaries("args"),
    boundaries("count"),
-   typechecked("default", "string"),
+   typechecked("target", "string"),
    typechecked("defmode", "string"),
    typechecked("show_default", "boolean"),
    typechecked("overwrite", "boolean"),
    typechecked("argname", "string", "table"),
-   typechecked("convert", "function", "table"),
    typechecked("action", "function")
 }, Argument)