Many changes listed below. - Introduce the first version of the user doc, most of the simulator parameters are detailed. - Add a fast intra-frame SIMD implementation of the LDPC BP flooding (SPA) decoder. - Change GSL Gaussian distribution generation function from the Box-Muller to the Ziggurat method which is faster. - Bug fix: in the fast event generator, when the event probability is null then fill the event vector with non event values to avoid border effects. - The channel type is given to the modem directly in the parameters instead of an argument to the build factory function. - Add the possibility to display a subset of frames in the debug mode and with an inter frame level higher than 1. - Fix the error tracker replay function when using BEC or BSC channels by adding USER_BEC and USER_BSC channels that use events from a given file. - In the CLI arguments, shorten the 'debug' word to 'dbg', same for 'frame' to 'fra'.