Fixes my bad on past attempt to deal with BOM (#1130)

Previously write bom segment wrote garbage instead of actual
byte order mark on every system.
With this I remove a NIH fix and add a system-dependent definition for
download file encoding, so on Windows there would no need to fix BOM
and on Linux there's no need to remove BOM for scripting with Downloaded file

PixivDownloadHandler.py

@@ -248,7 +248,7 @@ def download_image(caller,
 
                 # write to downloaded lists
                 if caller.start_iv or config.createDownloadLists:
-                    dfile = codecs.open(caller.dfilename, 'a+', encoding='utf-8')
+                    dfile = codecs.open(caller.dfilename, 'a+', encoding=caller.platform_encoding)
                     dfile.write(filename_save + "\n")
                     dfile.close()
 

PixivUtil2.py

@@ -65,6 +65,10 @@ def win_getpass_with_mask(prompt='Password: ', stream=None):
         return pw
 
     getpass.getpass = win_getpass_with_mask
+    platform_encoding = 'utf-8-sig'
+else:
+    platform_encoding = 'utf-8'
+
 
 script_path = PixivHelper.module_path()
 
@@ -1624,13 +1628,6 @@ def main():
         os.makedirs(directory)
         __log__.info('Creating directory: %s', directory)
 
-    # write BOM
-    if start_iv or __config__.createDownloadLists:
-        if not os.path.isfile(dfilename) or os.path.getsize(dfilename) == 0:
-            dfile = codecs.open(dfilename, 'a+', encoding='utf-8')
-            dfile.write(u'\uefbbbf')
-            dfile.close()
-
     # Yavos: adding IrfanView-Handling
     start_irfan_slide = False
     start_irfan_view = False