* Implemented the 'RDXPORT_COMMAND_AUDIOSTORE' web API call in
'web/rdxport/audiostore.cpp', 'web/rdxport/rdxport.cpp' and
'web/rdxport/rdxport.h'.
* Added an 'RDAudioStore' class in 'lib/rdaudiostore.cpp' and
'lib/rdaudiostore.h'.
* Modified the Desk Gauge widget in 'rdlibrary/disk_gauge.cpp'
and 'rdlibrary/disk_gauge.h' to use the 'RDAudioStore' class
[fixes GitHub issue #000035].
* Fixed a bug in 'Makefile.am' that broke the 'make install' rule
when using DESTDIR.
* Fixed a bug in 'icons/Makefile.am' that broke the 'make install'
rule when using DESTDIR.
* Fixed a bug in 'rlm/Makefile.am' that broke the 'make install'
rule when using DESTDIR.
* Fixed a bug in 'scripts/Makefile.am' that broke the 'make install'
rule when using DESTDIR.
* Fixed a bug in 'xdg/Makefile.am' that broke the 'make install'
rule when using DESTDIR.
* Fixed a bug in 'rdselect/Makefile.am' that broke the 'make install'
rule when using DESTDIR.
* Fixed a bug in 'web/rdxport/Makefile.am' that broke the
'make install' rule when using DESTDIR.
* Fixed a bug in 'configure.ac' that cause an incorrect VERSION
string to be generated.