get_contrast.matrix: create a contrast.matrix to be used with limma's fit function
In axelmuller/geometric2: NURSA annotation aid

create a contrast.matrix to be used with limma's fit function

1 2	get_contrast.matrix(path2contrast_file = "contrasts.txt", my_design = design, lmFit_out = fit)

`path2contrast_file`	the default is contrast.txt which is a table that contains the contrasts. It should have a column named Formula in which the contrast based on groups are given and anoter column named Contrast which gives a title for each contrast.
`lmFit_out`	output of lmFit function
`design`	this is a design object created with teh get_design() function its default value is design