Xpdf rc path Compatibility with Code Freezing Tools

[mush42]

Hi @ashutoshvarma

Changes

This PR makes generating xpdf_rc file path dynamic. The path is obtained using one of two methods:

1. Environment variables (highest priority): if there is an environment variable named PYXPDF_RC_PATH it will be used.
2. Using the appdirs package, we generate the file inside the Os specific user application config path taking care of returning a unique path per each instance (installation) of the pyxpdf_data package using a md5 hash of the poppler data path.

Rationale

The changes proposed in this PR are required to make the package compatible with code freezing tools such as PyInstaller as these tools disregard the site-packages directory, and package the stdlib as a zip file.

Best Regards,

[ashutoshvarma]

Thanks for the PR @mush42! Also apologies for the late reply, It was a busy week for me.
I will try to review it by this weekend, hope you don't mind

[mush42]

Hi @ashutoshvarma

Any news about the status of this PR?

Thanks.