Fix usage message, fix README, small code improvement

README.md

@@ -9,10 +9,10 @@ It has the following command line options:
 ```
 i18n.py [OPTIONS] [PATHS...]
 
--help : prints this help message
--recursive : run on all subfolders of paths given
--mods : run on installed locally installed modules
--verbose : add output information
+--help, -h : prints this help message
+--recursive, -r : run on all subfolders of paths given
+--installed-mods : run on locally installed modules
+--verbose, -v : add output information
 ```
 
 The script will preserve any comments in the template.txt or the various .tr files, associating them with the line that follows them. So for example:
@@ -32,4 +32,4 @@ If the mod's source changes in such a way that a line with an existing translati
 
 ```
 ##### not used anymore #####
-```
+```

i18n.py

@@ -52,12 +52,12 @@ def print_help(name):
     print(f'''SYNOPSIS
     {name} [OPTIONS] [PATHS...]
 DESCRIPTION
-    {' ,'.join(options["help"])}
+    {', '.join(options["help"])}
         prints this help message
-    {' ,'.join(options["recursive"])}
+    {', '.join(options["recursive"])}
         run on all subfolders of paths given
-    {' ,'.join(options["mods"])}
-        run on installed locally installed modules
+    {', '.join(options["mods"])}
+        run on locally installed modules
     {', '.join(options["verbose"])}
         add output information
 ''')
@@ -128,7 +128,7 @@ def get_modname(folder):
 #If there are already .tr files in /locale, returns a list of their names
 def get_existing_tr_files(folder):
     out = []
-    for root, dirs, files in os.walk(os.path.join(folder + '/locale/')):
+    for root, dirs, files in os.walk(os.path.join(folder, 'locale/')):
         for name in files:
             if pattern_tr_filename.search(name):
                 out.append(name)