gvle: remove header

The `iostream' header is duplicated in the main file.
utils: improve the Package class

We prefer to use the default constructor and the clear() function
instead of ` = ""'.
package: fix typo

Fix typo in four CMake scripts.
gvle: update the files management

- The dialog used to start a new project has been removed. Now we use a
  regular file dialog. It does enable to choose a directory anywhere, to
  be the recipient of a package.
- The Global VPZ features have been removed.
- The regular file chooser dialog is used to open a vpz file, and the
  older vpz chooser dialog has been removed.
(closes #82)
value: update POD functions in Set, Map and Matrix

We update getDouble and getInt in value::Set, Map and Matrix classes.
These functions return POD data: const and & are unnecessary.
utils: fix Path with old Boost and old VLE

We need to fix the changes in VLE API about Package for old Boost
filesystem version.
utils: update test_package to Win32

* The ::setenv() function is not available in the POSIX version of
  Win32. So, we use the ::_putenv() function.
* The ::Sleep function requires the Windows.h header.

TODO: use the ::_putenv() on Mingw32 and ::_putenv_s() with real Win32
API.
utils: update the test_package with VLE changes

We update the unit test in test_package with the Latest VLE changes
(split between source and binary package). (closes #68).
utils: update Compress functions with libarchive v2/v3

We improve the functions in Compress with libarchive v2 and v3. We split
source code in two part. libarchive v2 and v3 are too different.
doxygen: downgrade doxyfiles to 1.7

The Doxygen 1.8 is unavailable on all target platforms. We downgrade the
doxyfile with Doxygen 1.7.
vle-1.1.0-beta1
template: remove the REQUIRED keyword in pkg-config

The FindVLE and FindGVLE does not have the same behaviour between CMake
and PkgConfig modes: the PkgConfig requires vle or gvle.

So, we remove the REQUIRED keyword in the pkg_check_modules for both
template FindVLE and FindGVLE. (closes #87).
win32: fix missing libarchive dependencies

When packing the windows installer, the dependencies of libarchive
were missing.
win32: fix the search path using HKEYs in cmake

When using the instaler, the search path used for vle has to rely
default HKEY value.
cmake: fix the error message in gvle

the message was the same as in vle.
win32: fix the predefined variables for Boost

In SpawnWin, boost variables that ar used to find boost were
not defined as 8.3 path
win32: fix the test_package test

Setting the vle home using a boost::filsesytem::path requires to
format the path string with string() function.
cmake: library dirs in FindVLE and FindGVLE

the library dirs can be empty in the case, for example, of an install in /usr/
on linux using pkg-config. These empty variables should not lead to errors in configure
when using FIND_PACKAGE_HANDLE_STANDARD_ARGS.
cmake win32: fix FindVle and FindGVLE for 64 bits

The Hkeys have a different place in the registration base.
THe search path for vle and gvle is modified