Modify speed to slider and add template fan entity

[aebgit]

proposed changes as per #9

• change speed select to slider (dirty hack, requires review, especially around line 166)
• also exposes a template fan entity

[ouaibe]

That's an interesting proposal to be considered:

• Makes the speed selection much more natural instead of using the switch

• Creates a helper/virtual fan using the base HA template with a few caveats:

  • The helper/virtual fan cannot control the oscillation angle - not part of HA's default fan entity
  • The preset modes have to be mapped to the fan's modes (natural, normal, etc.) - knowing that the fan doesn't have a dedicated on/off, it's part of the preset modes.

• The PR has to be split because it includes changes that are NOT related to this setting, namely the line modified for PR10

• The commented out section has to be removed entirely in a final PR.

Feel free to either make the changes to reduce the caveats or I will eventually look into this.