Add a convenience template, GetFixedWidthInt<typename T>, which evaluates to a
struct with a typedef named "type", which has a fixed-width integer type that
is exactly the size and signedness of T.
Add explanatory material and linking information for CompoundStmt, ContinueStmt,
BreakStmt, PredefinedExpr, IntegerLiteral, FloatingLiteral, ImaginaryLiteral,
StringLiteral, ParenExpr, UnaryOperator, OffsetOfExpr, UnaryExprOrTypeTraitExpr,
MemberExpr, CompoundAssignOperator, and ConditionalOperator.