Matlab: support create from memory, multiple files, and UTF-8

[MichaelCurrie]

https://github.com/openworm/tracker-commons/blob/master/src/Matlab/wcon_TODO.m

1) Support creating from memory 
2) Support loading from multiple files
3) Properly parse and write to UTF-8

I believe 2 is still outstanding, but 3 is now complete. Not sure about 1. Just thinking that perhaps tracking these as GitHub issues would be best, rather than a file.

@JimHokanson

[JimHokanson]

All 3 of these are outstanding issues. The first point could be done, but we really need an example to be worked out. The 3rd point is supported by the reader, but I'm borrowing a writer and I have no idea if they implemented UTF-8 support correctly.