Add Textedit

[RobLoach]

@brianwatling Used the rows system you put together for a textedit widget and it's looking pretty good! A few things I think we could improve...

• I updated some of the structure of nk_console to include a void* data. We may be able to leverage that for nk_console_row's nk_console_row_data to simplify the structure
• There is nk_console_row_child::columns. Could we re-purpose nk_console::columns for that?

Overall, the rows worked really well! Thanks so much for the help on it.

[brianwatling]

I updated some of the structure of nk_console to include a void* data. We may be able to leverage that for nk_console_row's nk_console_row_data to simplify the structure

This would definitely be great. What I did on nk_console_row was non-standard compared to the other widgets and I think it'd be great to make rows in line with the new style you've introduced. I did it that way in the first place mainly as a kludge because I was working on it outside this repo as an extension

There is nk_console_row_child::columns. Could we re-purpose nk_console::columns for that?

nk_console_row_child::columns records the original 'columns' count of the child widgets so we can set columns = 0 for all the children in a row and nk_console_row_render can be in charge of setting the row layout. I don't see an easy way to use nk_console::columns for that but definitely interested to see any ideas you have

[RobLoach]

What I did on nk_console_row was non-standard compared to the other widgets

What you did with the data structure inspired the change, so I can't take credit, and you definitely took the correct approach. Thanks a lot.

I'll go through another round of review before merging.