Redesign shaders

@v0lt in relation to 0e2e3b9, no offense there, but I think a more extensive redesign is needed.

Todo:
- [ ] 1. Move resources that contain the actual shaders' code
- [ ] 2. Delete now obsoleted shader-related settings, write the migration handler
- [ ] 3. Update the installer and portable version packer
- [ ] 4. Remove mpc-hc shader editor, it hardly has any use when the shaders are in separate external files
- [ ] 5. Improve mpc-hc shader selector from single panel to dual panel view (from [this](https://www.dropbox.com/s/so19a0fzbbhsxlg/mpc_hc_shaders_old.png) to [not quite, but something like this](https://www.dropbox.com/s/f8y5u4wdsipikyw/mpc_hc_shaders_new.png)). Maybe add a new property page in Options dialog for it?
- [ ] 6. Implement shader-selection presets

@XhmikosR, @Underground78, @Armada651 I need your opinions on 4, 5, 6.

Btw, when the next release is planned to take place? I'd like to time this PR accordingly and finish it at least a month before the release, to give enough time to nightly-test and update translations.