Include the value for constants in popup menus.
Fix crashes when trying to evaluate an expression that is value-dependent.
Fix crashes when trying to evaluate an initializer expression
when the initializer is on a different decl.
Fix crashes when trying to evaluate an expression and the type isn't known.
Fix crash in building HTML when encountering a macro with non-ASCII
characters in it.
Move value hints from the popup menu to a tooltip.
Fix newlines and tabs in macros for value hints.
Limit value hints to 32 characters.
Refactor truncation logic into a _truncate helper function.