new checker 'regexp'

[Antonboom]

Closes #82

But I wonder that we lost syntax highlighting 🤔

P.S. https://youtrack.jetbrains.com/issue/GO-17040/Proposal-highlight-regexp-string-in-testifys-assert.Regexp-NotRegexp

[coveralls]

Pull Request Test Coverage Report for Build 9601905089

Details

• 38 of 43 (88.37%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 93.661%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/checkers/helpers_pkg_func.go	11	13	84.62%
internal/checkers/regexp.go	14	17	82.35%

Totals
Change from base Build 9601011094:	-0.06%
Covered Lines:	2172
Relevant Lines:	2319

---

💛 - Coveralls

[ccoVeille]

Just one readability remark, but LGTM 👍

Btw isPkgFnCall is a great addition 🎉

[coveralls]

Pull Request Test Coverage Report for Build 9607884797

Details

• 39 of 44 (88.64%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 93.664%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/checkers/helpers_pkg_func.go	11	13	84.62%
internal/checkers/regexp.go	15	18	83.33%

Totals
Change from base Build 9607744222:	-0.06%
Covered Lines:	2173
Relevant Lines:	2320

---

💛 - Coveralls