Add an OCR text layer to scanned PDF files

OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched. Main features: - Generates a searchable PDF/A file from a regular PDF - Places OCR text accurately below the image to ease copy / paste - Keeps the exact resolution of the original embedded images - When possible, inserts OCR information as a "lossless" operation without rendering vector information - Keeps file size about the same - If requested deskews and/or cleans the image before performing OCR - Validates input and output files - Provides debug mode to enable easy verification of the OCR results - Processes pages in parallel when more than one CPU core is available - Uses Tesseract OCR engine - Supports the 39 languages recognized by Tesseract - Battle-tested on thousands of PDFs, a test suite and continuous integration