Use strong typing for header serialization

[brantburnett]

Motivation

Eliminate the use of reflection when serializing and deserializing headers.

Modifications

Split header serialization into Primitive and List methods and call the correct method based on the schema type rather than determining at runtime using reflection.

Results

Compatibility is the same, but performance and trimming should be better. Still doesn't support object serialization at this time.

[brantburnett]

/merge

[brantburnett]

/merge