Better debugging & logging

[ccrisan]

Is your improvement proposal related to a problem? Please describe.

• There are no automatic (CI-provided) debug builds. I have to build myself a variant with debugging details.
• All log records have the same log level: DEBUG.
• Logging on network must be enabled & configured at compile time.

Describe the solution you'd like

• Automatically provide DEBUG builds via CI.
• Add separate log levels (e.g. DEBUG, INFO, WARNING, ERROR).
• Allow enabling & configuring network/UDP logging at runtime (extra API call or device attribute).
• Provide syslog-compatible log record format.