RFC for structs with undefined layouts.
General grammar/spelling/copy-editing.
Remove security from the RFC.
Mention the lint in the detailed design.
Write up the upstream FFI issue a little.
Move "Drawbacks" section after "Detailed design"

Having "Drawbacks" earlier in the document than "Detailed design" makes
it awkward to discuss drawbacks that reference details of the design.
This encourages authors to either violate causality by referencing
details before they are introduced or to neglect the "Drawbacks" section
entirely and just sprinkle the discussion of drawbacks throught
"Detailed design".
Randomisation can be used for fuzz testing.
Mention DST + field reordering.
Resolve the lint + extern fn question.
RFC: Rename `StrBuf` to `String`
Merge remote-tracking branch 'huonw/struct-repr'
Accept RFC 18
Merge remote-tracking branch 'pcwalton/rename-strbuf'
Renaming StrBuf is RFC 19
Merge remote-tracking branch 'bstrie/drawbacks'
RFC: pattern expansion in macros
Fixed an implementation bug
Note rustdoc limitation
Update PR numbers on RFC 20