Alpha v0.2.6

Self-Observability

• Updated metrics prefix to otelcol and expose command line argument to modify the prefix value.
• Batch dropped span now emits zero when no spans are dropped.

Processors

• Extended Span processor to have include/exclude span logic.
• Ability to choose strict or regexp matching for include/exclude filters.

Receivers and Exporters

• Added Carbon receiver and exporter.
• Added Wavefront receiver.