change: when trying to use parabolic interpolation a warning is now shown.

Since parabolic interpolation is no longer supported (because it can generate
incorrect results), a warning is now shown when reading the input file.
Instead of 3P interpolation, 4P will be used and the warning will be shown.
change: added support for cross-compiling from linux to windows.

This requires gcc-mingw to be installed on the system.
change: replaced some variables with constant values to #defines.

This is a backport of changes from clTraceo and was originally
intented to improve performance on OpenCL devices.
change: replaced timing method.

getRUsage() was returning incorrect results in the OpenCL version, because
it returns cpu time instead of elapsed time. To clarify: when running on
2 cores at 100% usage each, for 1 second, CPU time would be 2 seconds,
while actually elapsed time is only 1 second.
By using the clock() function we now get actual elapsed time.
Made Makefile more verbose. Added note for GCC bug number 7263.

To make it easier to read compiler output when building the distribution
pacakge, some spacing text has been added ( somthing like "Building
cTraceo for Linux i686".

The GCC (and specifically mingw) bug causes the message:
'warning: imaginary constants are a GCC extension [enabled by default]'
to be shown. This warning is incorrect (because imaginary constants are a
feature of C99) and cannot be disabled. See:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7263
for more info
Added preliminary support for doxygen. This addresses isuue #4.

For now only dependency/inclusion graphs are generated.
Function documentation still needs to be adapted.
Merge branch 'development' of github.com:EyNuel/cTraceo into development
minor change to Makefile
Changed number or rays used in example case

During testing the example had been set up to cast 3500 rays to verify that
the model can handle large numbers of rays correctly (it can).
This was causing problems when run on a user's laptop, so the number of
rays was now reduce to a more reasonable 100 rays.
added option --killBackscatteredRays. This closes issue #16.

the commandline switch --killBackscatteredRays terminates ray propagation
as soon as a ray inverts it's horizontal propagation direction.
corrected travel time interp. at box exit in solveEikonalEq(). closes #19

bug detected by Orlando:
Emanuel, I noticed that there is a small bug in seikeq.for: ray
coordinates are linearly interpolated at the box limits but travel times
are not. Thus, travel time information is fine but at the last ray point.
I guess that the C equivalent of seikeq.for has the same problem. This is
hard to spot but generates wrong results when a timefront is to be
calculated.

Cheers

Orlando
corrected travel time interp. at box exit in solveEikonalEq(). closes #19

bug detected by Orlando:
Emanuel, I noticed that there is a small bug in seikeq.for: ray
coordinates are linearly interpolated at the box limits but travel times
are not. Thus, travel time information is fine but at the last ray point.
I guess that the C equivalent of seikeq.for has the same problem. This is
hard to spot but generates wrong results when a timefront is to be
calculated.

Cheers

Orlando
Merge branch 'development' of github.com:EyNuel/cTraceo into development
fixed missing command line switch --version.

shorthand '-v' was already implemented, but the long version was missong.
added note on cTraceo's coordinate system in solveEikonalEq()
added preliminary implementation of drawWaveguide.m. Addresses #11.
added a cautionary note to an eigenray example case.

This example case makes use of the regula falsi method for determining
eigenrays.
added reference to github wiki to comment header of all source files.
command line switches are no longer case-sensitive.

This should help reduce mistyping issues.
moved options from local variables to external structure.

Also introduced a macro for creating log file output.
Preparation step for addressing issues #5 and #17, ie, allow specifying
output file name, and ssp file name.