Remove gogit and major refactoring (#2)

* Fix typo in readme

* Reimplement all git methods without go-git

* Rename repo pkg to git, add gitconfig methods

* Improve tests for configuration reading

* Rename package file to io and move RepoFinder there

* Refactor printers

- Remove smart printer
- Decouple printers from git repos with interfaces
- Update printer functions
- Remove unnecessary flags
- Add better remote URL detection

* Update readme and go.mod

* Add author to git commit in tests

Otherwise tests will fail in CI.

* Install git before running tests and don't use cgo

* Add better error message, revert installing git

* Ensure commit message is in quotes

* Set up git config before running tests

pkg/git/config_test.go

@@ -0,0 +1,93 @@
+package git
+
+import (
+	"testing"
+)
+
+// cfgStub represents a gitconfig file but instead of using a global one, it creates a temporary git repo and uses its local gitconfig.
+type cfgStub struct {
+	repo *testRepo
+}
+
+func newCfgStub(t *testing.T) *cfgStub {
+	r := testRepoEmpty(t)
+	return &cfgStub{
+		repo: r,
+	}
+}
+
+func (c *cfgStub) Get(key string) string {
+	cmd := gitCmd(c.repo.path, "config", "--local", key)
+	out, err := cmd.Output()
+	if err != nil {
+		return ""
+	}
+
+	lines := lines(out)
+	return lines[0]
+}
+
+func TestGitConfig(t *testing.T) {
+	tests := []struct {
+		name        string
+		configMaker func(t *testing.T) *cfgStub
+		key         string
+		want        string
+	}{
+		{
+			name:        "empty",
+			configMaker: makeConfigEmpty,
+			key:         "gitget.host",
+			want:        "",
+		},
+		{
+			name:        "valid",
+			configMaker: makeConfigValid,
+			key:         "gitget.host",
+			want:        "github.com",
+		}, {
+			name:        "only section name",
+			configMaker: makeConfigValid,
+			key:         "gitget",
+			want:        "",
+		}, {
+			name:        "missing key",
+			configMaker: makeConfigValid,
+			key:         "gitget.missingkey",
+			want:        "",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			cfg := test.configMaker(t)
+
+			got := cfg.Get(test.key)
+
+			if got != test.want {
+				t.Errorf("expected %q; got %q", test.want, got)
+			}
+		})
+	}
+}
+
+func makeConfigEmpty(t *testing.T) *cfgStub {
+	c := newCfgStub(t)
+	c.repo.writeFile(".git/config", "")
+
+	return c
+}
+
+func makeConfigValid(t *testing.T) *cfgStub {
+	c := newCfgStub(t)
+
+	gitconfig := `
+	[user]
+		name = grdl
+	[gitget]
+		host = github.com
+	`
+	c.repo.writeFile(".git/config", gitconfig)
+
+	return c
+}