* add gosched calls to UART
* add UART.flush() stubs for all supported architectures
* add comment un uart.go on flush functionality
* uart.writeByte as base of UART usage
* fix NXP having duplicate WriteByte
* fix writeByte not returning error on some platforms
* add flush method for fe310 device
* check for error in WriteByte call to writeByte
Some targets used capital PullUp/PullDown, while the documented standard
is Pullup/Pulldown. This commit fixes this mismatch, while preserving
compatibility with aliases that are marked deprecated.
Go 1.19 started reformatting code in a way that makes it more obvious
how it will be rendered on pkg.go.dev. It gets it almost right, but not
entirely. Therefore, I had to modify some of the comments so that they
are formatted correctly.
Do it all at once in preparation for Go 1.18 support.
To make this commit, I've simply modified the `fmt-check` Makefile
target to rewrite files instead of listing the differences. So this is a
fully mechanical change, it should not have introduced any errors.