Fix bug: make sure the cut-out region is computed correctly
Switch back to the original configuration mechanism for a_spin
Automatically load the locations of the radial boundaries
The values we read in are actually ln(r)
Compute the photon grid by input data such as lnrmin and lnrmax
Add a parameter 'O' to let the user change the output file names
cuda_gl_interop.h may cause errors; skip it when OpenGL is disable
Assume "usgdump2d" and the fieldline files are in the same directory
Fix bug: grid path is now correct even at the current directory
Output intensity and optical depth in single precision
Switch between a wind Tp/Te and a disk Tp/Te by looking at beta
Fix bug: correct the equation for magnetic field
Ensure endian correctness
u and b are vectors; their components are contravariant