Updates for LÖVE 11

[geoffbeier]

This changeset contains two categories of fixes:

1. Update the demo GUI tool to work with LOVE 11.3
2. Address issues that were found when testing load/save after that.

For (1) the changes:
a. update to the 11.x fork of LoveFrames that is being maintained by @linux-man
b. change any color literals to use components in the range (0,1) instead of (0,255)
c. move usage of deprecated love.filesystem functions to current versions.
d. fix a field name that was probably incorrect for a long time but now causes an assertion failure in LoveFrames.
e. reflect changes to LoveFrames skin API

For (2) the changes:
a. Make the version check not fail if the expected version == the found version when loading a lua file.
b. Replace references to globals freq and bits that are not defined in sfxr.lua in the wav export code with locals rate and depth.

[idbrii]

Thanks for your work on this PR! sfxr is pretty useful and it's nice to have a working UI.

Edit: Nevermind. If you run love demo like the instructions say, you don't get this error. The error is because I used love . from within the demo directory.

I swear this PR used to work for me (on 11.2?), but now I get "Error: main.lua:4: module 'sfxr' not found:" because sfxr.lua is in the directory above the demo.

To fix, add this to main.lua:

package.path = package.path .. ";../?.lua"

(Not sure why using love.filesystem.setRequirePath doesn't work either.)

[idbrii]

One change missed in this update was using the supported version of getDirectoryItems. The callback is no longer supported so the save/load dialogs never showed any files. Fix: idbrii@0da9d70