Re-wrote from scratch in Golang

- Re-implemented the project in Golang, and deprecated Python entirely
- Implemented several new, long-requested features
- Refactored cheatsheets into a separate repository

internal/sheet/copy.go

@@ -0,0 +1,51 @@
+package sheet
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path"
+)
+
+// Copy copies a cheatsheet to a new location
+func (s *Sheet) Copy(dest string) error {
+
+	// NB: while the `infile` has already been loaded and parsed into a `sheet`
+	// struct, we're going to read it again here. This is a bit wasteful, but
+	// necessary if we want the "raw" file contents (including the front-matter).
+	// This is because the frontmatter is parsed and then discarded when the file
+	// is loaded via `sheets.Load`.
+	infile, err := os.Open(s.Path)
+	if err != nil {
+		return fmt.Errorf("failed to open cheatsheet: %s, %v", s.Path, err)
+	}
+	defer infile.Close()
+
+	// create any necessary subdirectories
+	dirs := path.Dir(dest)
+	if dirs != "." {
+		if err := os.MkdirAll(dirs, 0755); err != nil {
+			return fmt.Errorf("failed to create directory: %s, %v", dirs, err)
+		}
+	}
+
+	// create the outfile
+	outfile, err := os.Create(dest)
+	if err != nil {
+		return fmt.Errorf("failed to create outfile: %s, %v", dest, err)
+	}
+	defer outfile.Close()
+
+	// copy file contents
+	_, err = io.Copy(outfile, infile)
+	if err != nil {
+		return fmt.Errorf(
+			"failed to copy file: infile: %s, outfile: %s, err: %v",
+			s.Path,
+			dest,
+			err,
+		)
+	}
+
+	return nil
+}