Read file descriptor efficiently

[Devessier]

We must have a flexible method to read.

Firstly, we will have to read from STDIN or from a regular file. Secondly, cryptographic algorithms don't all use a buffer of the same size to compute operations.

That is, we must:

• Read from a given file descriptor
• Lazy read the file descriptor, to read only what we need to
• Fill a buffer of a given size from an internal buffer, which is itself filled by read call

[Devessier]

When STDIN read mode is activated, we must start a loop that reads until the end.

Ctrl + D breaks the reading and launches command evaluation. It only does that only when there is no previous character on the line. (Probably does that automatically breaks STDIN?) We must test how things work.