to apply the new side bar icons i found 2 easy ways to do so
1-go to (Packages folder) make a folder call (Theme - Default) "you can name that folder to anything as ST use the empty sublime-theme file as a reference not the folder that contains it" ,drop your icons folder in there ,then create an empty file with the name of your currently applied theme.
|Theme - Default
*now everytime you apply a new theme just change the (???) to the theme name.
2-drop the icons folder in your theme folder ,right next to your (???.sublime-theme) file and the icons will be applied automatically.
.in both ways i found that i don't need to change or add any lines to the theme files.
.if you want to use the default icons that came with the latest rev ,do the same as the first step & delete or rename the icons folder to something else.
.for specific type of language (css , less ,etc..) use the instructions made by facelessuser in p.2 ,and put the (???).tmPreferences file right next to the icons folder.