Initial commit
first commit
develop parser

parse bulletml, top level action and top level bullet
develop parser

bullet, direction, speed
develop parser

add Actor class
support IE
add changeDirection, changeSpeed and nested action
add accel parser
add parser for wait, vanish, repeat
add coverage tool
add parser for actionRef and bulletRef
add fireRef
add samples
fix parse empty element
add test parse sample-xml
add assets for sample
add visitor
support IE
add sequence method
refine sample, test