Add error code descriptions

[pavel-kirienko]

Currently, whenever the firmware enters the Fault state (in other words, begins execution of the task Fault), Kucher displays the error code and says "elaboration not available". This is not cool. We need to make it display proper error messages as documented in this table: https://kb.zubax.com/display/MAINKB/Error+codes

The firmware has several tasks:

• Idle
• Fault
• Beep
• Run
• HardwareTest
• MotorIdentification
• LowLevelManipulation

They are indexed starting from zero. Each task may fail; upon failure, it returns an 8-bit error code, where value 0 is reserved to indicate success and hence can't appear among error codes. The error coding is therefore two-dimensional; for example, the error code 2 for the task Idle means "Hardware test failed", and the same code 2 for task Hardware Test means "DC voltage error".

Kucher should contain a YAML resource file listing the textual description of each error code for each task; the file should be read once at startup and used to look-up error descriptions.

[pavel-kirienko]

Paging @dimracer FYI