COMP: implicit cast scope name to C++-string in IOobject::scopedName
- handles 'const char*' and allows a check for an empty scope name
COMP: avoid potential name conflict in local function (Istream)
- reportedly some resolution issues (unconfirmed) with Fujitsu clang
- previously introduced `getOrDefault` as a dictionary _get_ method,
now complete the transition and use it everywhere instead of
`lookupOrDefault`. This avoids mixed usage of the two methods that
are identical in behaviour, makes for shorter names, and promotes
the distinction between "lookup" access (ie, return a token stream,
locate and return an entry) and "get" access (ie, the above with
conversion to concrete types such as scalar, label etc).
