docs: Copyedit my randomly assigned sections of the manual
trie: rm workaround for issue #3469
trie: inline the other TrieSet wrapper methods
trie: make the TrieSet impl public
remove obsolete purity workarounds
auto merge of #5501 : catamorphism/rust/manual, r=graydon

r? @graydon
auto merge of #5503 : thestinger/rust/trie, r=pcwalton
libsyntax: Stop parsing `pure` and `static`
libsyntax: Introduce the new `assert!` macro; make `assert` no longer a keyword
librustc: Remove the `const` declaration form everywhere
libsyntax: Stop parsing `const`.
librustc: Add explicit lifetime binders and new lifetime notation in core/std/syntax/rustc
test: Add lifetime binders and new-style lifetime parameters to the test suite
libsyntax: Stop parsing old lifetime syntax
libcore: Fix obsolete syntax in extfmt