fixed lots of bugs.
Merge branch 'master' of https://github.com/yuye-liu/BlackWings
fixed stage over 50 bug.
add overbuy weapon layer and ui.
Add EncryptUserDefault class.
change normal enemy dispatch style.
修改了飞机寻路方式，实时变更目标。暂测无异常。
修改飞机转向时间为匀速。
Merge pull request #36 from fusijie/master

fixed lots of bugs.