Bibtexautocomplete

- Add `-w --overwrite` and `-W --dont-overwrite` flags
- Fix flag `-f` being ignored in query pre-condition checks, leading
to skipping queries even if new data could be obtained.

- Add semantic scholar lookup
- Add `--mark` and `--ignore-mark` option and behavior
- Allow using `-q --only-query` to change lookup order
- Remove DBLP author disambiguation numbers (DBLP would sometimes return `John
Doe 0002`, which you don't want in your file)
- Fix rejection of some valid DOIs on URL check
- A few under the hood improvements and code cleanup

- Add global exception catches to resume work if a single lookup fails
- Fix websites returning invalid URLs leading to errors (issue [8](https://github.com/dlesbre/bibtex-autocomplete/issues/8), part 2)

- Fix trying to decode non-text doi response (issue [8](https://github.com/dlesbre/bibtex-autocomplete/issues/8))
- Add entry name to error/warning messages

- Allow for infinite timeout with `-t -1`
- Increase default timeout to 20s as crossref consistently times out
- Add per DB progress meters below the progress bar

- Fix `btac` script not installing due to bad setup.py options (6)