fixed 'BytesBuffer has no length' for haxe 3.0.1

Tests failed when i used haxelib install elebeta-format 1,0,0

```
################################################################################
###   UNIT TESTS - Neko (local)                                              ###
################################################################################
haxe  unit_tests.neko.hxml
format/csv/Tools.hx:148: characters 25-33 : haxe.io.BytesBuffer has no field length
format/ett/Reader.hx:168: characters 17-27 : haxe.io.BytesBuffer has no field length
make: *** [neko] Error 1
```

so i updated format.csv.Tools getBufContents() and 
format.ett.Reader readUntil()
and tests pass with this update.