GCC 4.7 compilation fixes. Now builds on debian wheezy beta2

clarify binding of function (by specifying 'this')
Boost filesystem Ver 2/3 transition

This is kind of a workaround to avoid having to maintain two variants.
Explanation: between Boost 1.42 and 1.52 there was the transition to a
reworked version of the filesystem library, itroducing some breaking changes
The new version distinguishes much clearer between the native and the
generic representation of paths -- which becomes relevant when porting
to non-POXIX operating systems.

Actually the intention was to use the generic path representation in all
configuration; currently this distinction is moot, since we're caring
only for POSIX systems.

So the workaround is to use the fsys::path::string() function, which
is available in both versions, but changed meaning to yield the native
string. Later, when able to deprecate older Boost versions, we should
switch to generic_string()
rebuild Lumiera package on Debian/Wheezy (pre-release)

this effort is a step towards upgrading to Wheezy (the upcoming
Debian stable release). Here, we've just applied the fixes to get
compilation going; the resulting package has some known broken stuff.
Most notably, the Lumiera application won't start up (due to some problem
with finding plug-ins)

Note: this is still the code base from 0.pre.01 (last year)
rebuild Lumiera package on Ubuntu/Precise  // Linking tweaks

the attempt to rebuild the old Lumiera package on 12.04 (LTS)
failed due to the unresolved problems with our internal library
dependencies. Added some tweaks to get the compilation going