New memisc release 0.99.17.1 with new capabilities for data preparation

A new release 0.99.17.1 of my package memisc has been published on CRAN. The new release has the following improvements:

• mtable() results now include a legend for significance symbols.
• A codeplan() function creates a data frame that describes the structure of an "importer" or "data.set" object. Such "codeplans" can be used to copy the "item structure" or code plan from one object to another.
• The subset() method for "importer" objects now accepts the names of variables to be selected also as a character vector.
• Dollar and double-bracket operators for "importer" objects are available to facilitate creating codebooks for individual variables.
• Summary statistics for models in calls to mtable() can be selected via options or list arguments.
• toLatex() method for mtable() results warns about unescaped TeX specials
• A dublicated_labels() function shows and describes duplicated value labels. The importer methods for SPSS (spss.system.file() and spss.portable.file()) files use this to warn about duplicated labels.
• Dates are properly imported from SPSS files and their representation in codebooks is improved.
• Operators %#%, %##%, and %@% make it easier to manipulate annotations and other attributes of objects.