Adapt to settings changes

- Issue #25 Adapt to settings changes
- Don't update the settings file when values are missing, just silently use the defaults
Integrated suggestions, ST2, file/folder exclude

Integrated suggestions from @FichteFolle
Support path_exclude_patterns and file_exclude_patterns to exclude files from being tracked in the history
Corrections for ST2 (timestamp calculation)
Better handling of timestamp format change
Added suport for exclude filename/path

Issue #22
consolidating path_exclude and file_exclude patterns

Simpler implementation of exclusion patterns
Consolidate path and file exclusion patterns
Update FileHistory.sublime-settings
Deleting from quickpanel reopens with updated list

See issue #24 for details ("Deleting an entry from the quick panel should reopen it with the entry removed").  
Also corrected some spelling mistakes in the comments.
Re-open panel at last position after deletion

Doesn't work correctly currently because of SublimeText/Issues#222 but
this is the best we can do.

Closes #24.
Catch exception when loading history file fails

Fixes #27.
Add setting for re-include path patterns

Closes #22.
Update a few comments in the settings file
Revise README and delete settings sections

We have the settings explained in the settings file itself and also a
small overview of available settings in the Features section.

Also move one screenshot to the top because that way users can more
quickly see what this plugin does.
Some minor refactoring wrt cleaning up callbacks
small enhancements

Make sure the updated_history is defined when the history json.load fails
Make sure the selected index compensates for the deleted entry
support for daily history file backup

Support for storing a daily backup of the history file.  To turn off backups, change this setting to 0 (zero).
support for daily history backup, misc changes

Support for storing a daily backup of the history file.
Move "SETTINGS_FILE " to the class
Reduced indent to 2 spaces
Misc corrections

Moved INDENT_SIZE and DEFAULT_TIMESTAMP_FORMAT to the class definition
Removing unnecessary debug statement
Removed code to select previous entry after a delete (will now select "next" entry as exprected
Bug fix when previewing file open in another group

A bug in SublimeText will cause the quick-panel to unexpectedly close trying to show the preview for a file that is already open in a different group, so simply don't display the preview for files already open in a different group (Fixes #23)
Create 1.6.0.md
Release 1.6.0