Provide simpler / less error-prone API

[Marcono1234]

Problem solved by the enhancement

As pointed out in this comment on the Rust forum (and subsequent comments) and in this Reddit comment, Struson's API is currently difficult to become familiar with for new users, and relying on panics to enforce correct API usage instead of relying on the compiler is non-idiomatic and error-prone.

Enhancement description

Keep the current JsonReader and JsonWriter API because it is most flexible. But provide additional API which is simpler and more intuitive to use (at the cost of potentially not exposing all JsonReader and JsonWriter features). The new API should be built on top of JsonReader and JsonWriter.

But don't use Drop for implicitly closing arrays or objects (or performing similar fallible actions) because it cannot propagate errors.

Alternatives / workarounds

• Don't add new API but instead adjust JsonReader and JsonWriter
  However, this might prevent using them in some use cases where they can currently be used.
• Don't perform any API changes at all, and if necessary try to adjust the documentation making the intended usage clearer

[Marcono1234]

An initial prototype has been implemented, see

• source code in src/reader/simple.rs and src/writer/simple.rs
• tests in tests/simple_reader.rs and tests/simple_writer.rs

However there are the following open questions:

• Should the naming of the API ("simple API"), the traits, structs and methods be adjusted?
• Should the module structure be changed?
  Currently the API is under reader::simple and writer::simple.
• Is the API usable for real world use cases? Can it be improved? Is functionality missing?
• Do you consider the usage of Box<dyn Error> for array and object reading and writing methods to be limiting? Do you have suggestions for alternatives, which don't make the function arguments cumbersome to implement?
• ...

Any feedback is appreciated!