sugar sum now supports complex sugar vector expressions

sugar mean implements the double pass algorithm for numeric and complex cases (#134)

more C++ support for Rcomplex: Rcomplex& operator+=( Rcomplex&, const Rcomplex& ) Rcomplex operator/( Rcomplex, double )

Internal refactoring/simplification of all api classes. Api classes are now parameterized by a class for the storage policy instead of a template as before.

Dots and NamedDots handle the border case when ... is missing (#123)

If the macro RCPP_DO_BOUNDS_CHECKS is defined, vector classes will perform bounds checks. This is turned off by default because it kills performance. #141

Array no longer generates spurious warnings. #154

Added the concept of lazy vectors. A lazy vector is similar to a sugar expression, but it only knows how to apply itself, i.e. we cannot call operator[](int) on it. This is used for implementation of create and fuse

create can now also be used as a free function. For example: IntegerVector x = create(1,2,3) ;. When used as a free function, create chooses to create a lazy vector of the highest type. For example, create(1,2.0) makes a lazy vector of type REALSXP (what makes sense for double).

Added the list function. It takes a variadic list of arguments and makes an R list from it. This uses the same underlying implementation as List::create but is nicer to use.

mapply was reimplemented using variadic templates. mapply now accepts a function as first parameter, then a variable number of sugar expressions.

Array gains a fill method to initialize all its data to the same value.

is<> was broken.

Initial implementation of ListOf. ListOf<T> is similar to List but it only exposes constructors that take T objects and methods that maintain this requirement. The implementation differs from Kevin Ushey's implementation in Rcpp, which IMHO tries to do too much.

New sugar functions Filter, Reduce and Map (synonym of mapply) #140.

New function Negate, Compose for intial attempt at functional programming and function composition #140.

Support for long vector has been added. Vectors are now indexed by the R_xlen_t type (64 bit on 64 bit platforms).

The header <Rcpp11> has been added. It just includes <Rcpp.h>, but I like it better to have #include <Rcpp11>

The Rcpp11 namespace has been added as an alias to Rcpp. So that we can type using namespace Rcpp11 ;

variadic trailing arguments can now be used in sapply (#189)

Logical vectors internally use the Rboolean type instead of int.

Added the syntax x != NA to test if something is not the missing value.

New sugar function import_n so that we can do import_n( iterator, n ) instead of import( iterator, iterator + n) ;

New sugar function enumerate (#153).