Replacement of cython with numba (routing)

[doc78]

• use of numba instead of cython for parallel computations in the routing module: numba was already used in other parallelized functions in soil modules. Now this version extends the use of numba to the kinematic wave parallel routing module. The change allows to completely exclude the use of Cython in the whole Lisflood OS software with no performance loss and skipping further compilation steps and potential run issues when porting kinematic wave compiled library to other systems/hardware. Numba use a Just in time (JIT) compilation that compiles python routines at runtime, generating optimized code and allowing parallelization by skipping the python Global Interpreter Lock (GIL) of specific parallelizable computation functions.
• xml files and documentation files are now updated removing the variables used by kinematic wave parallel routing module and skipping the steps for the compilation of Cython routing functions. Numba parameters in xml files should be used instead of the old kinematic wave ones to allow or disable parallelization on multiple CPUs hardware systems.
• documentation of lisflood flags is now updated

[emiliano-gelati]

This is great!