Step/subStep support

[LefterisXris]

Steps' structure should not be strict. e.g. A step should act like a tour if there are some sub-steps below it.
This requires Structural changes.

Example Tree rendered Structure:

.
├── 1st Step Group - Controller/
│   ├── Controller Step 1/
│   │   ├── Controller Step 1.1
│   │   └── Controller Step 1.2
│   ├── Controller Step 2
│   └── Controller Step 3
├── 2nd Step Group - Service/
│   ├── Service Step 1
│   ├── Service Step 2
│   └── Service Step 3/
│       └── Service Step 3.1
└── 3rd Step Group - DB/
    ├── DB Step 1
    ├── DB Step 2/
    │   ├── DB Step 2.1/
    │   │   └── DB Step 2.1.1
    │   └── DB Step 2.2
    └── DB Step 3