move build to build3 to avoid naming conflict with Bullet 2.x

fix build error in BasicGpuDemo
Thanks to joen66 for the report here:
https://github.com/erwincoumans/bullet3/issues/5

build3/bin2cpp.lua

@@ -0,0 +1,48 @@
+function convertFile(filenameIn, filenameOut, stringname)
+	print("\nfilenameOut = " .. filenameOut)
+		local f = assert(io.open(filenameIn, "rb"))
+		
+		local fw = io.open(filenameOut,"w")
+		fw:write(string.format("char %s[]={", stringname))
+    local block = 10
+    while true do
+      local bytes = f:read(block)
+      if not bytes then break end
+      for b in string.gfind(bytes, ".") do
+        fw:write(string.format("char(%u),", string.byte(b)))
+      end
+      --io.write(string.rep("   ", block - string.len(bytes) + 1))
+      --io.write(string.gsub(bytes, "%c", "."), "\n")
+      fw:write(string.format("\n"))
+    end
+    fw:write(string.format("\n};"))
+	
+end
+
+
+ newoption {
+    trigger     = "binfile",
+    value				=	"binpath",
+    description = "full path to the binary input file"
+  }
+  
+   newoption {
+    trigger     = "cppfile",
+    value				=	"path",
+    description = "full path to the cpp output file"
+  }
+  
+  newoption {
+    trigger     = "stringname",
+    value				=	"var",
+    description = "name of the variable name in the cppfile that contains the binary data"
+  }
+  
+   newaction {
+   trigger     = "bin2cpp",
+   description = "convert binary file into cpp source",
+   execute = function ()
+    convertFile( _OPTIONS["binfile"] , _OPTIONS["cppfile"], _OPTIONS["stringname"])    
+ 
+   end
+}