Group rename script (edited)

void Main()
{
    var all_groups = new List<IMyBlockGroup>();
    GridTerminalSystem.GetBlockGroups(all_groups);
    var numbering = true; //Set to false to remove numbering.

    for (int cur_group_index = 0; cur_group_index < all_groups.Count; ++cur_group_index)
    {
        var cur_group = all_groups[cur_group_index];
        string group_name = cur_group.Name;

        if (group_name.ToLower().StartsWith("rename to "))
        {
            var blocks_in_group = cur_group.Blocks;
            string base_name = group_name.Substring(10);

            if(numbering){
                for (int cur_block = 0; cur_block < blocks_in_group.Count; ++cur_block)
                    blocks_in_group[cur_block].SetCustomName(base_name + ((cur_block == 0) ? "" : (" " + (cur_block + 1).ToString())));
            } else {
                for (int cur_block = 0; cur_block < blocks_in_group.Count; ++cur_block)
                    blocks_in_group[cur_block].SetCustomName(base_name);
            }
        }
        else if (group_name.ToLower().StartsWith("prefix with "))
        {
            var blocks_in_group = cur_group.Blocks;
            string prefix = group_name.Substring(12) + " ";

            for (int cur_block = 0; cur_block < blocks_in_group.Count; ++cur_block)
                if (!blocks_in_group[cur_block].CustomName.ToLower().StartsWith(prefix.ToLower()))
                    blocks_in_group[cur_block].SetCustomName(prefix + blocks_in_group[cur_block].CustomName);
        }
    }
}