acoust press is now correctly saved to matfile when using linear array.

This closes #18.
Also started using assert() to validate input to functions.
Placing the source on the range box boundary no longer causes segfault.

The range box is now automatically resized by 0.1 meters to include the
source and the followin error is shown:
"WARNING: source's range coordinate is equal to range box boundary."
"         Range box has been automatically resized to include the"
"         source position."
"         Adjust range box (rBox) to include the source position to"
"         avoid this warning in the future."

This closes #13
Merge branch 'development' of https://github.com/EyNuel/cTraceo into development