React Chessboard Expandable

This is a fork of the
react chessboard
project which supports an expandable chessboard. It supports a new fen, I have
horribly named modified fen which supports this expandable chessboard
requirement

Modified FEN

I have introduced a FEN string modification to support my requirement of an
expanding board.

$3

- The board should be able to expand from the original 8x8 board 1 square at a
time
- Pieces should be able to occupy any of the newly created squares

$3

Normal FEN looks like this

``
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
`

I have introduced a few new special characters

| Character | Description |
| --------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| # | This character should show up at the starting of the row defining the 8th rank |
| $ | This character should show up before the character on the a file |
| E | This character simply a non existent square. The purpose of this character is to disambiguate square with no piece and empty space |

$3

#### Board with 1 row as the 9th rank

`
8/#rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
`

#### Board with 1 row as the 0th rank

`
#rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR/8
`

#### Board with a file before the a file

`
#1$rnbqkbnr/1$pppppppp/1$8/1$8/1$8/1$8/1$PPPPPPPP/1$RNBQKBNR
`

#### Board with a file after the h file

`
#$rnbqkbnr1/$pppppppp1/$9/$9/$9/$9/$PPPPPPPP1/$RNBQKBNR1
`

#### Board with a few squares added on top of 8th rank

`
2EEEEE1/#rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
``

#### Note

I know its a horrible name, I should have named it something like expandFen or
fenPlus, but I am too lazy to change all occurances of it in my code.