Towards proper unwinding

[gaborcsardi]

Machinery is there now, "just" have to use it.

• RParquetAppender.cpp
• RParquetOutFile.cpp
• RParquetReader.cpp
• arrow-schema.cpp
• base64.cpp
• broken.cpp
• cpp-utils.cpp
• dictionary-encoding.cpp
• encodings.cpp
• protect.cpp
• r-base64.cpp
• r-utils.cpp
• read-metadata.cpp
• read-pages.cpp
• read2.cpp
• rwrapper.cpp
• snappy.cpp
• test.cpp
• write2.cpp

[gaborcsardi]

Actually, I am not going to properly fix all of these, because it is a lot. But I'll handle the memory errors that valgrind detected. It seems like I only need to wrap Rf_error() for them.

[gaborcsardi]

Will be handled properly in #103.