Guide: patterns.

Fixes #4417.
Guide: iterators
Guide: array subscript notation
Refactor BitV internals to not use macro, reduce duplication
Manual: add information about //!

Fixes #16569
librustc: Fix field offsets for packed structs.
Add test for passing/getting packed structs with ffi.
work around MinGW linker bug for ASLR on Windows

Closes #16514
Explain modulo in the guide.

Fixes #15954
Fixing bitvset is_disjoint, fixes #16587
Make comment about small bias in %.

Fixes #16354.
Fix underflow bug in core::str::Searcher::new for haystacks of length < 20
Add a test for the fix of issue 16589
A few minor documentation fixes
auto merge of #16582 : Gankro/rust/bitv, r=alexcrichton

This was bothering me (and some other people). The macro was necessary in a transient step of my development, but I converged on a design where it was unnecessary, but it didn't really click that that had happened.

This fixes it up.
auto merge of #16583 : steveklabnik/rust/gh16569, r=pcwalton

Fixes #16569
Rename Nullable::Some to Nullable::NotNull
auto merge of #16585 : steveklabnik/rust/random_remarks, r=pcwalton

Fixes #15954 and #16354.
auto merge of #16588 : thestinger/rust/aslr, r=pcwalton

Closes #16514
serialize: add json::{Integer,Floating} to parse large integers properly

[breaking-change]