Expand reflection options behavior.

[fr33r]

Description

These changes automatically expend reflection option behavior such that:

• by default, all methods that start with "Set" will be excluded.
  • as outlined in Effective Go, setters should start with "Set", and setters are not eligible for this reflection behavior.
• a new options, WithColumnNameMapping, can be provided to override the default name determined for a column.

Rationale

• Without WithColumnNameMapping, the only way specify a custom name is by constructing the entire column definition (either through code or via file definition). This makes it far more convenient.
• Using Effective Go as a guide, we are able to safely exclude methods that would conventionally be identified as "setters" from being included within the reflection process.

Suggested Version

v1.2.0

Example Usage

obj := Foo{
  FirstName: "Han",
  LastName: "Solo",
}

table, err := morph.Reflect(obj, morph.WithColumnNameMapping("FirstName", "given_name"))
if err != nil {
  panic(err)
}