Initial work on embedding file name and package info into the logger
object

* log4cl.asd (:log4cl-test): Add test-file-category.lisp
* src/defs.lisp (*logger-truename*): new variable
* src/impl-package.lisp (package #:log4cl-impl): export new stuff
* src/logger.lisp (struct logger): change depth to flags
(%get-logger): add flags argument
(logger-file): new function to return the file name of where logger was instantiated
* src/pattern-layout.lisp (pattern-layout):
(parse-category-extra-args): lift up function from the parse-extra-args defmethod
(parse-extra-args #\c): as above
(format-category): lift up function from define-pattern-formatter #\c
* tests/test-layouts.lisp (make-expected): handle strings too
* tests/test-logger.lisp (:log4cl-test): rename speed to test-speed
* tests/test-speed.lisp (test-speed): as above
* tests/test-file-category.lisp: tests for file category
Add %g %G and %F to pattern layout (package/rest/file parts)

* src/logger.lisp (make-logger-flags): add assert that either both or
  none of package start/end indexes are specified

  (%get-logger): update docstring, and change flags argument to be
  either a list of arguments to make-logger-flags or a number encoding
  flags directly

* src/pattern-layout.lisp (parse-extra-args, format-categories):
  implement %g %G and %F formats

* tests/test-file-category.lisp:
  (test-file-category-3,test-package-category-1,test-package-category-2):
  tests for above
Tests pass
Make log:config show error for non-existing explicitly specified logger
instead of creating it silently
Switch to (log-setup) for dotted package test
Use :reader appender-filename instead of the defmethod, and add
exported appender-backup-filename accessor, which simplified daily appender tests
Fix DAILY-FILE-APPENDER to rollover pre-existing log file
Add source-file-logger for each source file, and embed reference to it into leaf loggers
* src/pattern-layout.lisp (#\c): docstring
(#\C): format the categories excluding package
* tests/test-file-category.lisp (test-file-category-1): tests for %C and %g
* src/pattern-layout.lisp (pattern-layout): added %C %g and %F to docstring
Added INHERITED-LOG-LEVEL function

* src/logger.lisp (inherited-log-level): new function
* src/impl-package.lisp (#:log4cl-impl): export
* src/logger.lisp (logger-descendants): don't return duplicates
* src/logger.lisp (%get-logger): When logger is first instantiated in a file,
and then retrieved with no file bound (ie in the REPL or such), do not reset
the file.
* src/pattern-layout.lisp (pattern-layout): docstring for new formatting flags
(format-categories): length calculation was wrong when precision specified
(format-info): prefix/suffix and empty skip
(format-string): ditto
(simple-format-catogories): ditto
(compile-pattern-format): ditto
* tests/test-layouts.lisp (test-pattern-layout-optional): tests for prefix/suffix
Change the source-file logger to be keyed in the package logger
by its full namestring rather then just file-namestring.

In addition, allow retreiving source-file-loggers by partial name, returning
first match.
* src/configurator.lisp (show-logger-settings): Don't consider source file logger interesting
based on its children
Change default category separator to dot
Fix instantiating a source file logger, with parent that was split
into multiple categories, and parent not existing yet, was creating
parent as source-file-logger too
Adjust test suite for "." being default category separator now
Get rid of (log4cl-impl self) logger, just use plain log4cl-impl, fix
(log:config) not to print log4cl-impl logger, change default pattern layout
to two-line one with file and package