Pdftitle

- `--version` option added
- build system is migrated from setup.py to pyproject.toml

- new feature: the use of metadata if exists. it is not enabled by default.

- reorganized the project structure and files (see additional notes for v0.12 below)
- fixes bug 31
- pdfminer version updated
- new feature: converts latin ligatures (ff, fi, fl, ffi, ffl, ft, st = Unicode FB00-FB06) to individual characters by default
- started using standard logging, thus the log prints go to stderr

- functionally same as 0.10, including some pylint fixes.

- --page-number argument added. Related issue is [here](https://github.com/metebalci/pdftitle/issues/22).
- potentially a fix implemented for some files having non-zero Trm[1] and Trm2[] elements. This change might cause different outputs than previous versions of pdftitle. This is related to the issue raised [here](https://github.com/metebalci/pdftitle/issues/24).
- verbose and error messages improved.
- pdfminer version updated.

- retrieve_spaces function is made non-recursive.
- eliot algorithm is implemented for [this issue](https://github.com/metebalci/pdftitle/issues/18), test file is woo2019.pdf
- eliot-tfs option is implemented for eliot algorithm.
- stack trace was printed only in verbose mode, this behavior is changed and now stack trace is printed always if there is an error.