Some README changes and ability to enter in .csv empty strings

[ebelevics]

Hi,
I am really thankful for this package, as it simplifies app translation a lot. Only thing what I found missing is that I cannot leave in .csv empty fields, and I get error during generation. I need empty fields to seed translations to keys later on. So far I managed to add " " to empty field, but would prefer if I had option in pubspec.yaml ability to set generator convert empty field to "" or even to "KEY_NAME" in .arb files.

Other thing what I found was in README, that you have use "dart run flutter_pseudolocalizor" to generate arb files. After greater digging I found that you need to use "dart run arb_generator", which makes sence, and everything did work after. Please correct this mistake.

[defuncart]

@ebelevics Thanks for using arb_generator :) Apologies for the confusion about what command to run, I originally copied the README from another package that I've published, and forgot to update that section 🙈

It is required that for the base language has a text value, otherwise an exception is raised. This, however, isn't documented in the README. The majority of the CSV parsing piggy-backs off flappy_translator, a package which I maintain. As of now, there are no plans to autogenerate a translation based on the key name, however this is an interesting idea, and one I'll create an issue for on flappy_translator.