整理代码，略微提升部分小程序的性能

parts/scenes/app_dropper.lua

@@ -1,10 +1,11 @@
 local gc=love.graphics
-local rnd=math.random
-local int,max=math.floor,math.max
+local rnd,int,max=math.random,math.floor,math.max
+local setFont,mStr=FONT.get,GC.mStr
 
 --This mini-game is written for TI-nSpire CX CAS many years ago.
 --Deliberately, some grammar mistakes and typos in the 'great' list remained.
 --So no need to correct them.
+
 local perfect={"Perfect!","Excellent!","Nice!","Good!","Great!","Just!","300"}
 local great={"Pay attention!","Be carefully!","Teacher behind you!","Feel tired?","You are in danger!","Do your homework!","A good game!","Minecraft!","y=ax^2+bx+c!","No music?","Internet unavailable.","It's raining!","Too hard!","Shorter?","Higher!","English messages!","Hi!","^_^","Drop!","Colorful!",":)","100$","~~~wave~~~","★★★","中文!","NOW!!!!!","Also try the TEN!","I'm a programer!","Also try minesweeperZ!","This si Dropper!","Hold your calculatoor!","Look! UFO!","Bonjour!","[string]","Author:MrZ","Boom!","PvZ!","China!","TI-nspire!","I love LUA!"}
 local miss={"Oops!","Uh-oh","Ouch!","Oh no."}