Move the include flags for files in the source tree from
configure.ac to Makefile.am where they belong. Also use
AM_CPPFLAGS instead of CFLAGS/CXXFLAGS to make sure the
files in the build/source tree are always picked up first.
Also, remove the include/libsigrok sub-directory from the
search path, thereby making the <libsigrok/> prefix mandatory
when building libsigrok itself. This matches the convention
already imposed on users of the library.
Gnuplot doesn't have any "official" file name extension(s). It uses
(at least) two different types of files basically:
- "control files": These can have many different somewhat commonly
used extensions such as .gpi, .gnu, .gnuplot, .gp, .plt, .gih,
others. These files don't contain data, only Gnuplot commands such
as 'set yrange [75:105]', 'set ylabel "foo" offset 1', and so on.
- "data files": This is what libsigrok reads and writes. These files
contain actual data to be graphed by Gnuplot (with the help of a
specially-crafted control file, see above). The data is usually in
a tab-separated format. The common file extension is usually .dat,
though many others are possible as well.