lua: fix options submodule

It polluted the global namespace, instead of exporting the function
properly.

For now, keep it compatible by explicitly keeping the bogus export.

Also fix a mistake in the manpage example.

player/lua/options.lua

@@ -30,7 +30,7 @@ local function typeconv(desttypeval, val)
 end
 
 
-function read_options(options, identifier)
+local function read_options(options, identifier)
     if identifier == nil then
         identifier = mp.get_script_name()
     end
@@ -101,4 +101,9 @@ function read_options(options, identifier)
 
 end
 
+-- backwards compatibility with broken read_options export
+_G.read_options = read_options
 
+return {
+    read_options = read_options,
+}

player/lua/osc.lua

@@ -33,7 +33,7 @@ local user_opts = {
 }
 
 -- read options from config and command-line
-read_options(user_opts, "osc")
+opt.read_options(user_opts, "osc")
 
 local osc_param = { -- calculated by osc_init()
     playresy = 0,                           -- canvas size Y