Added safety try-catch to machine loading code, to avoid crashes for unexpected states.
Added callback doc for experience upgrade and chunkloader upgrades.
Merge branch 'OC1.3-MC1.6.4' of github.com:MightyPirates/OpenComputers into OC1.3-MC1.7.2
Adjustments for 1.7.
Merge branch 'OC1.3-MC1.7.2' of github.com:MightyPirates/OpenComputers into OC1.3-MC1.7.10