Changed location of class files.
Updated .Rbuildignore.
Fixed portable C++ code problem: "Other macros, typically upper-case, may be defined by the compiler or system headers and can cause problems. The most common issue involves the names of the Intel CPU registers such as CS, DS and SS defined on i586/x64 Solaris in <sys/regset.h> and often included indirectly by <stdlib.h> and other core headers."
http://cran.r-project.org/doc/manuals/r-patched/R-exts.html#Portable-C-and-C_002b_002b-code
Updated build file (small additions that may save trouble in some cases).