osx and crash corrections

Hi,
thanks for your work. i've been looking for good bidi solution and this one is brilliant.
found two issues that i should get corrected with my changes:
1. os-x build was failing due to the usage of dynamic length of array, which wasn't liked by the build. used dynamic allocation instead. also, the last gyp stage trying to export the icu libraries should be "none", so that node-gyp doesn't fail trying to create a static lib without sources.
2. had segment-faults/crashes in my usage scenarios, when using setLine, due to the persistent reference to the parent paragraph not using New, but rather a local variable.

hope it makes sense. i also updated to 53.

what do you think?

Thanks.
Gal.