Retrieve multiple layer effects

[sngjuk]

With various usages, recently I found that multiple layer effect is not readable with psd.js
and I found the reason is about info keyword 'lmfx' and 'lfx2'.

When there's only 1 layer stroke, it uses 'lfx2'
but if I added multiple layer strokes, it uses 'lmfx'
as current 'object_effects.coffee' only handles 'lfx2',
when it comes to multiple strokes (or multiple layer effect) it skips object layer info entirely.

this issue is resolved in #164

[sngjuk]

resolved #164