Recording process.versions allows us to be much more aggressive about
rebuilding binary dependencies whenever the version of Node/V8 might have
changed, even if the package was not just downloaded.
When we call readAndWatchFileWithHash, if the file does not exist, we
still want to add it to the watchSet with a null hash. Later, however, we
have to be careful we do not assume every file in watchSet.files exists.
- We don't want to do a bunch of parsing *per comparison* when sorting
a list of package version strings. package-version-parser's `compare`
(and server's `compare`, which it uses) both accept either a string
or a parsed record. By parsing explicitly with memoization, we avoid
a super-linear blow-up in the amount of parsing. This'll save someone
half a second, at least.
- Adjust profiling hooks and messages
- Expose `Profile` to isopackets
It's very useful to be able to include code only in production. It's
useful for React integration, but presumably also for many apps.
* Add prodOnly boolean flag alongside debugOnly in Package.describe
* Packages the set prodOnly to true auto-depend on isobuild:prod-only
(making them error in the old tool where prodOnly isn't supported)
* The `includeDebug` boolean build option is replaced by a string
named buildMode, which can be 'development' or 'production', just
like minifyMode.
Tested by self-test.
