feat: improve store_trace_reason with extract parameter store_trace_reason() used embedded code to extract reason based on the location passed to the function. This change adds support for extract keyword that is a Python expression eval'ed when the underlying function/method is called. All callers now set the extract parameter. The prior embedded code has been removed from store_trace_reason(). Failure to eval the expression results in an roundup.logcontext error severity log. Also updated docs. Also replaced env['REQUEST_URI'] with env['PATH_INFO'] for web based entry points as REQUEST_URI isn't documented as a required key and some other front end (e.g. zope, cgi) might not supply this.

#  - "path/to/folder"  # ignore folders and all its contents
#  - "test_*.rb"       # wildcards accepted
#  - "**/*.py"         # glob accepted
#  - "[a-z]+/test_.*"  # regexp accepted

# ignore files that are build utils and not executed
# code, or are deprecated.
ignore:
   - "roundup/cgi/TAL/talgettext.py" # utility command
   - "roundup/cgi/TAL/DummyEngine.py" # test harness
   - "roundup/cgi/apache.py"  # mod_python is deprecated
   - "roundup/install_util.py" # another build utlity
   - "roundup/dist"           # more build utils
   - "roundup/test"           # code used for testing