add missing redex-examples dependencies
racket/draw: fix serializaiton of bitmap drawing in `record-dc%`

Closes PR 14349
move delim-cont tests into a separate file
Add diagrams from Vincent's PADL paper to TR docs
Use prefix -> in the TR Guide examples

Also some minor fixes like using the more common
case-> form rather than case-lambda.
Add a TR Guide section about ->* and optional args
Add a top blurb to the TR Reference
Added support for weighted samples in `density' and `kde'

Also improved window width estimate
Updated types for `density' and `kde'
Sanitized `density' bandwidth calculation for very dense data sets

Now, for example, (plot (density '(0))) works.

Calculated bandwidth is now bounded by both 1e-308, below which
`kde' produces nonsense, and 1e-14 * max absolute value. The latter
bound ensures the bandwidth is wide enough to make a smooth-looking
curve even in the presence of floating-point rounding in the domain,
by ensuring that at least 100 floating-point numbers or so in the
domain get nonzero density.

It's a little weird to use the gap between floating-point numbers
for this, but it ensures density estimates aren't jagged because
of rounding (at least until you zoom in, in some instances), and
it's at least a decent method of estimating bandwidth for single-
sample density estimators.
Fixed some problems with 2D plots not rendering due to +nan.0 and +inf.0

The "view" coordinate system for 2D plots used to be the same as the
"plot" coordinate system, except possibly stretched in a way that
preserved endpoints. When the endpoints were close to extreme flonum
values like +min.0 or +max.0, and the 2D plot area determined that
there were enough floating-point numbers within the plot bounds to do
fast floating-point arithmetic without losing visual fidelity, some of
that arithmetic could overflow. Then +inf.0 and +nan.0 values would
passed to `set-clipping-rect', which would promptly throw up, as it
should.

Solution: like the 3D plot area, use a normalized view coordinate
system. Now stretched plot coordinates are translated and scaled to
[0,1]x[0,1], for which floating-point arithmetic won't overflow.
Update TR doc pkg dependencies
adjust error message for impersonate-struct to match its actual contract
clarify object=?
fix error message
Fix TR regression and use abstraction recipe

A function like (lambda (x) (lambda (y) y)) would cause TR
to fail in an internal metafunction. The fault was triggered
when the object y is abstracted to (0 0) and then the outer
lambda tries to abstract (0 0) and fails.

The problem was triggered by the new path index changes in
v6.0 because TR did not previously try to abstract objects
that occurs in the target type (now necessary for scope
lifting of path indices), which may contain non-identifier
objects.

This error didn't occur in another nearly identical (except
for one crucial identifier? check) code path, so this commit
also eliminates the duplication by abstracting.
fix typo in reference
setup/dirs: fix `get-apps-dir`

Affects the location of ".desktop" file installation, especially in
a Unix-style installation.
raco setup: fix the way that "stamp" is compiled for avoided files

Instead of claiing "beginning of time" and an empty SHA1, use
`file-stamp-in-paths` to get a proper stamp.

This fixes a problem when installing built packages into user scope
where the built packages refers to an installation-scope library
and SHA1s need to be checked to fix up file timestamps.
Improve type inference for ListDots

This provides better inference for the case when trying
to infer a ListDots in a negative position against a List
type. For example, when trying to apply `time-apply`.