Added NamedSelect and NamedGet APIs

[prasad83]

NamedSelect and NamedGet APIs to be consistent with Select and Get variants were missing.

Kindly consider this merge request.

[coveralls]

Pull Request Test Coverage Report for Build 135

• 0 of 26 (0.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.2%) to 66.578%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sqlx.go	0	9	0.0%
named.go	0	17	0.0%
<!--	Total:	0	26

Totals
Change from base Build 122:	-1.2%
Covered Lines:	1000
Relevant Lines:	1502

---

💛 - Coveralls

[adamantike]

Is there any chance for this PR to be reviewed? It would be really useful to have these as part of sqlx API.

[carpii]

Is sqlx no longer maintained, or is this pull request just waiting for test coverage to be implemented?

Would be a useful addition, the sqlx API is a little inconsistent without it

[maranqz]

Is sqlx no longer maintained, or is this pull request just waiting for test coverage to be implemented?

I hope the second. Could you add test?

Also, there is Named Queries in doc with an example.

arg := map[string]interface{}{
    "published": true,
    "authors": []{8, 19, 32, 44},
}
query, args, err := sqlx.Named("SELECT * FROM articles WHERE published=:published AND author_id IN (:authors)", arg)
query, args, err := sqlx.In(query, args...)
query = db.Rebind(query)
db.Query(query, args...)

[dlsniper]

Hello, @ardan-bkennedy, and I recently stepped in to help maintain this project. We are sorting the opened issues and pull requests and would like to know if you still NEED this merged. If so, can you please add tests to it? Thank you for your contribution.