Add RenderWithFile support

[dsxack]

Fix for #55

[codecov-io]

Codecov Report

Merging #56 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #56   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          14     14           
  Lines        1706   1708    +2     
=====================================
+ Hits         1706   1708    +2

Impacted Files	Coverage Δ
jen/statement.go	100% <100%> (ø)	⬆️
jen/group.go	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0c10b93...b817c4e. Read the comment docs.

[dave]

OK this looks good, and it's a valid addition. A few things:

1. Don't need GoStringWithFile... GoString is called with the fmt package formats with the #v verb, so adding a variation doesn't make sense.

2. We should tweak the internals of the Render function to use RenderWithFile(writer, f) instead of duplicating all the logic.

3. The Group type has a Render method too... it should probably have RenderWithFile also.

Thanks for the PR!

[dsxack]

Thank you for review! I'm going to fix remarks now

[dsxack]

I've done your PR comments

[dave]

Merged! Thanks!

[dsxack]

Thank you!

[dave]

I've tagged this release as v1.3.0.

Thanks very much!