replace with std.experimental.allocator

[Laeeth]

Hi.

It's not in shape for you to just accept, as I guess you might want to make use of the allocator optional.

And for deallocation, I do:
scope(exit)
csvAllocator.deallocateAll();

Once I have finished parsing CSV files. Probably a better way to do this!

[Laeeth]

fwiw when I tested just now on a 34 Meg file I only noticed mine being 10% faster, but I seem to recall it was much more previously (could be many things including runtime getting better). That took about 300 msec, so roughly 100 MB/sec. (My drive does 2.5 GB/sec).

might be interesting to look at this guy who claims astounding performance:
http://www.wise.io/tech/paratext
https://github.com/wiseio/paratext