Use own proc macro to generate code to deal with packets

[Dushistov]

Features:

• removes unnecessary dependicies
• more type safe code
• faster parser: 3x
  fixes separate protocol and implementation? #1

@lkolbly

Problems I found during conversation to usage of proc macro that I would like to disscuss:

1. I replaced the end of NavPosVelTime
   before:

    pos_dop: u16,
    reserved2: u16,
    pub reserved3: u32,

after:

    pos_dop: u16,
    reserved1: [u8; 6],
    heading_of_vehicle: i32,
    magnetic_declination: i16,
    magnetic_declination_accuracy: u16,

the last version is match documentation, while previous one not,
not sure how this works before

2. NavPosVelTime uses mm/s as speed units while NavVelNed uses cm/s
   according to documentation, but previous code for some reason treats NavVelNed
   as mm instead of cm, is it problem with documentation or with code?
   And side note NavStatus have similar fields with NavPosVelTime , but only one bit representation match according to documentation, all other fields has different format, though the same name and the same purpose.

3. Why negative nanoseconds values converted to 0, may be negative also valid value, or why they use signed integer instead of unsigned one?

4. May be use chrono function to validate date instead of convert it without check?

What missed:

• testing on real device (I am goging to do it tomorrow)
• full conversation of code with features=serial , I only partly converted it,
  because of how you plan to use AlpSrv is not clear for me,
  and looks like AlpSrv is removed in u-blox8 (https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_(UBX-13003221)_Public.pdf)
  But I convert what I can, and you can see how code improved, at now you don't need to use magic numbers for class/message id.

And comment from previous review:

The create_packet signature looks good to me (would it make sense to call it serialize

This is against idea that Builder is just the way to create packet, so you can not serialize builder, there is no sense in this operation, but you can create packet from builder. That's why I don't call it serialization.

[lkolbly]

full conversation of code with features=serial

Don't spend too much effort on this part - I want to totally rewrite how the serial library parts work, so if anything gets sticky with that, feel free to just comment it out entirely.

I'll look more at this later when I get a sec, but in general where the documentation and the code disagree I trust the documentation more.

[Dushistov]

Fixed issue with UbxPacketRequest that I found during
testing with real device.

so if anything gets sticky with that, feel free to just comment it out entirely

I did almost that.

[lkolbly]

I haven't gotten to the derive crate yet, but looking good so far.

[lkolbly]

Just that one comment about collecting over results, and then this looks good to me. Thanks for all your hard work on this!