Addition of the tool scandirpdf2txt

This release includes four tools :

naming_conventions.py & naming_conventions_do_rename.py to enforce some strict rules over the directory names in a file tree

check_jpegs for a fast sanity check of a jpegs file tree & check_jpegs_full for a deeper and slower sanity check

scandir2pdf for massive conversion from jpegs to pdfs.

new : scandirpdf2txt for massive conversion from ocred pdfs to txt files for the purpose of fast full text search with dedicated tools (google or else).

validated on 27K+ jpeg files, 1.2K pdfs.