InvDtBbyB: Inversing data frame block by block
In GlenDu/ODBbB: Operating on Data block by block

Takes any NxN data fame and inverse its data block by block based on the predetermination that we'll give to the fonction.

1	InvDtBbyB(Data = data(), lengthBlock = integer(), cls = c(), rs = c())

`Data`	Data frame that will be imported
`lengthBlock`	The length of the blocks that will be transposed.
`cls`	The columns that we want to include in the transposition.
`rs`	The rows of the first block. Based on this rows the function will select identically the rows of every other block.