This commit removes all unstable and deprecated functions in the standard
library. A release was recently cut (1.3) which makes this a good time for some
spring cleaning of the deprecated functions.
This commit cleans out a large amount of deprecated APIs from the standard
library and some of the facade crates as well, updating all users in the
compiler and in tests as it goes along.
This restructures tidy.py to walk the tree itself,
and improves performance considerably by not loading entire
files into buffers for licenseck.
Splits build rules into 'tidy', 'tidy-basic', 'tidy-binaries',
'tidy-errors', 'tidy-features'.
