raco setup: run Reference sequentially before other documentation

Otherwise, the Reference and Guide run concurrently, so the
Guide's section titles do not converge until a second run, which
forces many documents to a third run.
raco pkg update: setup collections of dependent packages

If package Y depends on package X, and package X is updated,
then include the collections of Y in the set passed to
`raco setup'.
Fixed file/md5's conversion for TR according to the documentation.
Move most of the `planet` collection to 'planet-lib'.
Move distributed places to their own package.
Build only some of the racket-test's dependencies in Travis.
Include eli-tester
move "scriblib" from "racket-doc" to "scribble-lib"
count ".scrbl" files as modules within a package

The set of relevant extensions should be made extensible, eventually.
move Scribble tests to "scribble-test"
adjust the places <-> distributed-places connection

Instead of a dynamic-require, the connection goes through a
structure-type property on a `remote-note%' instance.
move `planet/resolver' back to core

In consultation with Sam, partially reverts efba034e01. The default
module name resolver uses `planet/resolver' for the build-in
`(planet ....)' form. The `raco planet' command is still in
"planet-lib", though.
typo
update for moved drracket tests
fix (I think) a redrawing problem with the 102 chars column guide
fix `raco exe'
add "share", move "collects" back out of "lib", move "pkgs"

The "share" directory holds platform-independent files, while
"lib" holds platform-specific files.

In principle, the "collects" directory belongs in "share",
as does "doc". Those directories are put into "share"
by a Unix-style install, but left at top level for an
in-place install.

Packages in installation scope are put in "share" instead
of "lib", and the top-level Makefile puts development links
in "share/devel-pkgs".

The `configure' script now supports `--docdir' and `--collectsdir'.

Changed the version to 5.90.0.1.
distro-build: add support for source installers
fix problems with "collects" path and GUI executables
Remove extraneous syntax-class.