IO symbols don't follow established conventions

[e-kayrakli]

There are still some open interface discussions about the IO module, so some of these should probably wait, but some examples of these are

• io* enums and params:
  iokind, iostringformat etc should be camelCase: ioKind, ioStringFormat
• some methods:
  readstring, readbytes etc should be camelCase readString, readBytes
• some UPPERCASE_UNDERSCORED constants
  To say the least, this casing is uncommon in Chapel module code.

Arguably, some of these discussions will depend on some of the discussions in #6698, but I think some of them are more or less agreed upon and changes should be straightforward.

[dlongnecke-cray]

Since I'm the most recent person to touch this code, I'd be willing to slog through it and clean it up. I also share your distaste!

I think the IO module in particular is a prime example of exactly why a style guide is needed.

[bradcray]

I think the IO module in particular is a prime example of exactly why a style guide is needed.

I don't think anyone's argued it's not needed, it's just that nobody ever volunteers to take the lead on creating one.

[e-kayrakli]

I brought this up to IO stabilization subteam. It looks like this is good to close.