Add Boost dependency in configure

The configure.ac script requires Boost. The VLE 1.1 Win32 toolchain
splits Boost and VLE. So we add an m4 script to search boost on the
system.
rvle-1.1.0-beta1
win32: dynamically modify the path in onLoad

The windows path has to contain the path to vle install. To avoid modifying
the path for all applications, we set it in the R session before loading
the rvle.dll.
Update autotools scripts
rvle-1.1.0-beta2
README: add an rst file
Remove warning about Makefile.am

We remove the configure script from the repository to avoid the
following error if the user does not have use the ./autogen.sh.
(Closes #6, #7 and #9).

Two modes to distribute RVLE.

- User uses the Git repository:

	cd rvle
	./autogen.sh
	cd ../
	R CMD INSTALL rvle

- User uses the released tarball:

	R CMD INSTALL rvle_1.0.1-2.tar.gz
Add default autotools files
NEWS: update
rvle-1.1.0-beta3
rvle-1.1.0-beta4