SymbolTable issues when importing symbols from external modules

[sergisiso]

Simon Muller has reported some issues when using the SymbolTable resolve_import method:

• It fails to import target symbols with a name that varies in capitalisation from the corresponding symbol name used in the container from which it should be imported.
• The method seems to lack a ‘return’ statement just before the final conditional section starting with ‘if symbol_target:’. PSyclone raises a KeyError when successfully resolving a RoutineSymbol from a wildcard imports.