Feature: Provide a RTL generator

[dpretet]

In order to widely support feature #12 easily, a basic RTL generator must be developed to drop the top level code. It must generate the top level with any number of slave and master interface, and drop the switch stage with the correct parameter specifying the number of agents.

[dpretet]

To this task, the switch stages must be updated to use vectored parameters. Some parameters are described like that but not all.

For instance MST_ROUTES is correctly described:

        // Routes to the slaves allowed per master
        parameter [MST_NB*SLV_NB -1:0] MST_ROUTES = 16'hFFFF,

But not ID_MASK:

        // Masters ID mask
        parameter [AXI_ID_W-1:0] MST0_ID_MASK = 'h00,
        parameter [AXI_ID_W-1:0] MST1_ID_MASK = 'h10,
        parameter [AXI_ID_W-1:0] MST2_ID_MASK = 'h20,
        parameter [AXI_ID_W-1:0] MST3_ID_MASK = 'h30,