text-freetype2: Add chat line count property

Allows the ability to choose the number of chat lines when using the
"Chat log mode" feature.

Closes obsproject/obs-studio#1280

plugins/text-freetype2/data/locale/en-US.ini

@@ -3,7 +3,8 @@ Font="Font"
 Text="Text"
 TextFile="Text File (UTF-8 or UTF-16)"
 TextFileFilter="Text Files (*.txt);;"
-ChatLogMode="Chat log mode (last 6 lines)"
+ChatLogMode="Chat log mode"
+ChatLogLines="Chat log lines"
 Color1="Color 1"
 Color2="Color 2"
 Outline="Outline"