Clock RINEX

[gwbres]

This branch corrects, improves and integrates the Clock RINEX file format to the processing toolbox.
This is the last format that is required prior moving forward to PPP

• simplifies the Clock Record type
• improved and simplified inner types
• improved parsing method
• unlock a dedicated crate feature with dedicated methods
• introduce clock state interpolation
• add Clock RINEX to the User Context
• add a first visualization method, by adding this new type to -g --clk
• prefer Clock RINEX in navigation solving process when that is feasible
• Improved Rinex::Cargo.toml
• Improved Graph (-g) mode in both --clk and --orbit representation: do required calculations only once (render faster)
• Show only common sky content in SP3/CLK versus RADIO content