manual: "to" -> ".."
manual: remove unusual production name in match-expr grammar.
manual: fixes to match expression examples and explanation.
manual: remove 'analogy' between return and return. meaningless.
manual: avoid describing 'assert' as 'like check', note future removal.
manual: add 'item', remove statement that built-in types are keywords.
manual: example fixup.
manual: fix vec and str types to discuss definite / indefinite size.
manual: capitalize more examples properly.
manual: fix various examples.
manual: rewrite the section on type kinds.
manual: remove description of references (modes) from memory-slots section.
manual: fix bullet list.
manual: remove as many ~"" literals as possible.
manual: remove as many ~[] literals as possible.
manual: fix accidentally broken test.
manual: fix one more nit.
Fix tutorial-ffi tests
manual: Lightly copyedit the macros section
manual: Lightly copyedit the crates section