lazyindex: speed up __getitem__ This function is fairly performance sensitive, so we make a couple ugly tweaks: - keep all entries packed so we needn't test entry types - fold index lookup/load into unpack call to eliminate local variable setting

% basic
% unknown
*** [alias] unknown: command bargle is unknown
% ambiguous
*** [alias] ambiguous: command s is ambiguous
% recursive
*** [alias] recursive: circular dependency on recursive
adding foo
% with opts
C foo