Handle build.NoGoError
Fix panic when using line number pragmas.

This commit fixes an issue where generated files that use line pragmas would cause errcheck
to panic. This occurred because errcheck would try to look up the line from the file but
the file did not exist in the checker so an "index out of bounds" panic would occur.

The fix does not try to parse every generated file but instead opts to simply return the
line number and character position. The actual line itself is returned as blank.
Add line pragma test case.
Merge pull request #43 from benbjohnson/pragma-fix

Fix panic when using line number pragmas
optimization: use go/loader to load the entire set of packages/deps at once
Merge pull request #44 from robfig/master

optimization: use go/loader to load the entire set of packages/deps at once
Make compatible with the 1.3 branch of go.tools

Fixes #46
fix non error assignment to blank
Merge pull request #47 from foubarre/master

fix non error assignment to blank
detect unchecked type assertions
unit tests unchecked type assertions
Merge pull request #1 from foubarre/check-type-assertions

Check type assertions
Merge pull request #48 from foubarre/master

Optionally detect unchecked type assertions
Rename -types to -asserts