Make HorizontalSelector solid

* #set_to() should raise error when receiving unknown value
* Implement #can_set_to?
* Unit test for #set_to, #val and #can_set_to?
Handle unknown From account as customized
Merge pull request #66 from 5long/more-solid-account-selector

More Solid Account Selector
'polling' and 'new messages' flashing is now down by default poll hooks. after-poll hook gets passed new argumetnts num_total and num_inbox_total
HookContext#flash should fallback to log()

Not sure where it'd be used though.
Merge #70 'no-poll-flashing'

* Don't flash message when custom hooks before/after-poll are defined
* Pass num_total and num_inbox_total to after-pool hook
* Implement HookContext#flash
Revert "Use old 'syck' module for YAML parsing"

This reverts commit d8f17699fc830663221c429b9ec28bed689f6da8.
Add tool to convert YAML objects from syck to psych.
Use supmua.org for YAML_DOMAIN
Use different backup name as .bak already is used in lib/sup.rb and +x
add sup-psych-ify--- to SUP_EXECUTABLES
Only support Ruby 1.9.2+, dropping 1.8
Support loading legacy YAML for now.
Remove redundant self.instance_eval
Remove dead & deprecated code
Now sources.yaml migration is just load & save
Mention psych-ify in gemspec.post_install_message
Set yamler explicitly for 1.9.2
Merge pull request #75 from 5long/migrate-to-psych

Migrate to Psych
support setting the color of normal text

- message bodies
- system log
- inlined attachments

Not sure if I missed a spot