整理代码，Zframework添加数学扩展模块

Zframework/init.lua

@@ -4,6 +4,7 @@ LOADED=false
 ERRDATA={}
 
 --Pure lua modules (basic)
+MATH=       require'Zframework.mathExtend'
 COLOR=      require'Zframework.color'
 TABLE=      require'Zframework.tableExtend'
 STRING=     require'Zframework.stringExtend'

Zframework/mathExtend.lua

@@ -0,0 +1,19 @@
+local MATH={}for k,v in next,math do MATH[k]=v end
+
+local rnd=math.random
+
+MATH.tau=2*math.pi
+
+function MATH.sign(a)
+    return a>0 and 1 or a<0 and -1 or 0
+end
+
+function MATH.coin(a,b)
+    if rnd()<.5 then
+        return a
+    else
+        return b
+    end
+end
+
+return MATH