Revert autoadding of <> to custom argnames

spec/usage_spec.lua

@@ -137,7 +137,7 @@ describe("tests related to usage message generation", function()
             :add_help(false)
          parser:argument "inputs"
             :args "1-2"
-            :argname "input"
+            :argname "<input>"
 
          assert.equal(
             [=[Usage: foo <input> [<input>]]=],
@@ -151,7 +151,7 @@ describe("tests related to usage message generation", function()
          parser:option "--pair"
             :args(2)
             :count "*"
-            :argname{"key", "value"}
+            :argname{"<key>", "<value>"}
 
          assert.equal(
             [=[Usage: foo [--pair <key> <value>]]=],

src/argparse.lua

@@ -295,18 +295,18 @@ function Argument:_get_argname(narg)
    local argname = self._argname or self:_get_default_argname()
 
    if type(argname) == "table" then
-      return "<" .. argname[narg] .. ">"
+      return argname[narg]
    else
-      return "<" .. argname .. ">"
+      return argname
    end
 end
 
 function Argument:_get_default_argname()
-   return self._name
+   return "<" .. self._name .. ">"
 end
 
 function Option:_get_default_argname()
-   return self:_get_target()
+   return "<" .. self:_get_target() .. ">"
 end
 
 -- Returns label to be shown in the help message.