Fix leftover M3U8 injection vector, missing country codes, README sync

- Sanitize the channel number field for embedded double quotes; the
  previous fix (#1124) covered group/name/logo/epg but missed
  tvg-chno, leaving the same attribute-injection vector open via the
  "#" column.
- Add missing "kenya" and "nigeria" entries to COUNTRY_CODES so those
  channels get a tvg-country attribute in the generated playlist.
- Sync README.md and flag_order.txt with lists/: add missing flags for
  chile, egypt, saudi_arabia, indonesia, kenya, nigeria in their
  proper geographic groups.
- Add .gitignore for __pycache__/*.pyc.

flag_order.txt

@@ -22,6 +22,8 @@ taiwan
 # North & South Korea
 north_korea
 korea
+# Southeast Asia
+indonesia
 
 ############
 ## EUROPE ##
@@ -104,10 +106,12 @@ san_marino
 #################
 ## MIDDLE EAST ##
 #################
+egypt
 iran
 iraq
 israel
 qatar
+saudi_arabia
 turkey
 united_arab_emirates
 
@@ -116,6 +120,7 @@ united_arab_emirates
 ############################
 # Spanish-speaking
 argentina
+chile
 costa_rica
 dominican_republic
 mexico
@@ -133,4 +138,6 @@ trinidad
 ## AFRICA ##
 ############
 chad
+kenya
+nigeria
 somalia