Tag validation

[masihyeganeh]

It now validates tags.
It shows that C::TAG is wrong sometimes. we need to work on that.
simple_der now panics with Got unexpected tag Universal(2) instead of ContextSpecific(0) error.
It needs to parse a Number (Universal(2)) but C::TAG says it needs to see ContextSpecific(0) that is wrong.

And by the way, I added more default tags and implemented Display for it if you don't mind.

[masihyeganeh]

Correct me if I'm wrong, but based on this example:

Data-Structures DEFINITIONS ::=
BEGIN
  DataStructures ::= SEQUENCE
  {
     int              INTEGER,
     limitedString    UTF8String (SIZE(1..16)),
     optionalString   UTF8String OPTIONAL,
     enumerated       ENUMERATED {value1, value2, value3},
     optionalChoice   CHOICE
     {
        int1   [0] INTEGER,
        int2   [1] INTEGER
     }  OPTIONAL,
     sequenceOfString SEQUENCE OF UTF8String
  }
END

in places such as choice that there are [0] and [1], the C::TAG should be ContextSpecific(0) and ContextSpecific(1).
Also if there was AUTOMATIC TAGS after DEFINITIONS, then all Tags should be ContextSpecific(index of the element).

Other than that, it should always be Universal.

[masihyeganeh]

OK, I just added ability to parse AUTOMATIC TAGS and saving it as a boolean automatic_tags on model.
I see that you already extracting tag number in next_with_opt_tag.
Please help me with this.
if automatic_tags is true, this function should return increasing number for each tag.

[kellerkindt]

FYI: as long as (existing) tests do not pass, I do not consider a PR as ready