rename installed binaries to avoid name clashes and add manpages

The 2 older commits:
The names of the installed binaries are very generic which can clash with names of other executables installed on the system. In particular 'record' for fakenect is provided by other packages on Debian and Ubuntu. In order to avoid this problem, the installable demos have all been prefixed with 'freenect-' and record has been renamed into fakenect-record.

I believe these changes are harmless but please modify or reject them if there are any issues. However this renames are applied since a long time in Debian and Ubuntu packages so I believe it would be nice that libfreenect integrate them.

The more recent commit:
This commit adds manpages to fakenect executables. If the two previous are rejected, you can cherry-pick this one anyway by renaming  'fakenect-record' into 'record' (the substitution must be done also in the manpage)