Deal with common functions

[thiagomaf]

A few functions such as CSCprimers::load_fasta() or CSCprimers::get_fasta_annotation() are utility functions that will be necessary in CSCpromoters.

Ideally we would move such common functions to a new library rather than duplicating them.

We must decide whether to deal with that now or at the end of the work. As I see, the best solution would be to create a new library to host such functions (e.g. a new CSCfasta library).

[thiagomaf]

List of functions to deal with

• [x] CSCprimers::load_fasta()
• [x] CSCprimers::get_fasta_annotation()
• [ ] write_fasta()

[thiagomaf]

I will create a new CSCfasta library to keep all FASTA related functions. Ok?