Update inputs after merging IC regions overlap handling

------------------

Initial conditions are built from defined regions. The input names are built using the prefix `ic.`, the name of the

region to apply the IC, and the name of the phase (e.g., `myfluid`).

region to apply the IC, and the name of the phase (e.g., `myfluid`). The

following inputs must be preceded by the root `ic.`.

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

+-----------------------+------------------------------------------------------------------------+-------------+-----------+

|                       | Description                                                            |   Type      | Default   |

+=====================+=======================================================================+=============+===========+

| ic.regions          | Regions used to define initial conditions.                            | String      | None      |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

+=======================+========================================================================+=============+===========+

| regions               | Regions used to define initial conditions.                             | String      | None      |

+-----------------------+------------------------------------------------------------------------+-------------+-----------+

| allow_regions_overlap | Flag for allowing the user to decide whether particles will be         | Bool        | 1 (yes)   |

|                       | generated/initialized more than once on the areas where the IC regions |             |           |

|                       | have an intersection                                                   |             |           |

+-----------------------+------------------------------------------------------------------------+-------------+-----------+

| ranking_type          | IC regions are sorted during initialization. This input lets the user  | String      | Inputs    |

|                       | decide the ranking criterion, which can be one of the following:       |             |           |

|                       |                                                                        |             |           |

|                       | * inputs -- the order in the inputs file                               |             |           |

|                       | * volume -- the volume of each IC region                               |             |           |

|                       | * priority -- the priority value provided by the user in the inputs    |             |           |

+-----------------------+------------------------------------------------------------------------+-------------+-----------+

For a fluid phase, the following inputs can be defined.

The name of the DEM phases to be defined in the IC region and the packing must be defined.

+---------------------+------------------------------------------------------------------+-------------+-----------+

+----------------------+------------------------------------------------------------------+-------------+-----------+

|                      | Description                                                      |   Type      | Default   |

+=====================+==================================================================+=============+===========+

+======================+==================================================================+=============+===========+

| ic.[region].solids   | Solids type in this IC region (only one type per region allowed) | String      | None      |

+---------------------+------------------------------------------------------------------+-------------+-----------+

+----------------------+------------------------------------------------------------------+-------------+-----------+

| ic.[region].priority | Priority value for IC regions ranking as described above         | Int         | Max       |

+----------------------+------------------------------------------------------------------+-------------+-----------+

| ic.[region].packing  | Specifies how auto-generated particles are placed in the IC      | String      | None      |

|                      | region:                                                          |             |           |

|                      |                                                                  |             |           |

|                      | * n-cube -- n^3 particles per cell where n is an integer         |             |           |

|                      |                                                                  |             |           |

|                      | (NOTE: oneper is equivalent to 1-cube and eightper to 2-cube)    |             |           |

+---------------------+------------------------------------------------------------------+-------------+-----------+

+----------------------+------------------------------------------------------------------+-------------+-----------+

For each solid, the following inputs may be defined.