fix multi when  dis===0
dis!==0 && std===0 => mult = 1
fix some style
add two btn: switch and limit
v0.2.3
Merge branch 'dev'

* dev:
  v0.2.3
  add two btn: switch and limit
  fix some style
  dis!==0 && std===0 => mult = 1
  fix multi when  dis===0