[phobos] cacheIsBack and general policy suggestions

[Andrei Alexandrescu]

The introduction of cacheIsBack in std.algorithm.Map makes the unittests 
fail in release mode. I'm investigating the reason.

Please ALWAYS build unittest in both debug and release mode prior to 
committing. This can be easily done on Unixen by running

make -f linux.mak unittest

Also, all data members of Map have a trailing underscore but cacheIsBack 
doesn't. I'm not hung on any particular rule but mixing two conventions 
in the same module, let alone the same type, is just bad. That goes for 
a bunch of "if(" added in a module that used "if (" everywhere.

Please ALWAYS follow the conventions of at least the module you're changing.


Andrei