More control and Theme Elements

added an option to have different color and text for BSV (issue submitted by professor France Mentre)
added two vignettes showing how to simulate a PK , PK/PD and exposure response models from scratch.
added a switch to control theme_bw: base_size
added theming proposed by Benjamin Rich and arguments to add a table title and size.
added an argument to ensure alignment of strips between table and plot.
changing default rounding and padding for table numbers (proposed by Benjamin Rich)
added options to control the legends number of columns.
added hooks for more control on margins, strips etc.