Dax

Fix bug with upload threads

-Add support for pet scans inputs
-Add option to set results dir when running dax upload
-Fix bug in XnatUtils
-Add URL encoding for SLURM script
-Switch htmlparser for python 3.9 compatibility

*Xnatdownload: new "rename" option to put scan ID in filenames
*documentation updates
*fix for readthedocs to build "main" branch instead of "master"
*fix bugs related to first installing and setting up

The major change in this version is the complete removal of dax_settings.ini. Most settings are now in the yaml settings file. These settings are written by dax manager or can be manually typed. Also, credentials are now only read from ~/.netrc for XNAT and email servers.

Other changes include:
*fix issue 303, dax manager override error
*fix issue 291, logic issue in XnatUtils.has_resource
*fix issue 284, bug in processor parser
*fix issue 280, missing outlog on upload
*fix issue 299, bug in upload one sub-directory
*fix issue 283, all settings in redcap
*fix issue 289 and 256, dax manager will now re-run project automatically whenever the yaml changes to effectively rebuild whenever redcap changes
*support "session" argument in dax launch (internal bug report)
*handle spaces in file paths for Xnatupload (internal bug report)
*finish moving settings to redcap and get rid of dax_settings.ini and dax_templates, except for job_template
*documentation improvements
*new mode option in instances redcap to allow "upload only"

Changes in this version:
-randomly sort project order when launching new jobs
-handle instance disabled in REDCap
-improved error message for pyxnat db errors
-handle errors in redcap settings
-improved BIDS support
-documentation updates
-move templates to separate repo

-Add dependency for nibabel
-Add requirement for python 3