Symbol list icon mapping

SymbolList.m

    [self addSymbolMappingWithScopeSelectorString:@"meta.function, meta.method" imageName:@"symbol_list_function"];
    [self addSymbolMappingWithScopeSelectorString:@"meta.class, meta.interface-or-protocol" imageName:@"symbol_list_class"];
    [self addSymbolMappingWithScopeSelectorString:@"meta.module, meta.directive.module, source meta.implementation entity.name.type" imageName:@"symbol_list_module"];
    [self addSymbolMappingWithScopeSelectorString:@"meta.directive.define, meta.preprocessor" imageName:@"symbol_list_define"];
    [self addSymbolMappingWithScopeSelectorString:@"meta.tag" imageName:@"symbol_list_tag"];
    [self addSymbolMappingWithScopeSelectorString:@"markup.heading" imageName:@"symbol_list_heading"];