[queso/examples/bimodal] Adding new example 'bimodal' to QUESO examples. This example uses the Multilevel algorithm to sample from a bimodal distribution and reproduces the example presented in Prudencio&Chegung 2012, Section 4.1 A 1D Problem.
[queso/manual]: Including a new section 'bimodal' at the userś manual, which presents an example of the Multilevel algorithm being used to sample from a bimodal distribution. This example replicates the 1D problem (section 4.1) of the Multilevel paper (Prudencio&Cheung 2012).