Let ESC skip back to where the search started

When searching in the pager, pressing ESC will now skip back to where
the search started. This is useful when you want to quickly jump back to
where you started searching from.

Pressing RETURN will still stop the search and leave the cursor where it
is.

Being able to press ESC to go back somewhat improves on the first half
of #257, related to searching from
the current position to the end.

m/pager.go

@@ -141,7 +141,7 @@ Searching
 ---------
 * Type / to start searching, then type what you want to find
 * Type ? to search backwards, then type what you want to find
-* Type RETURN to stop searching
+* Type RETURN to stop searching, or ESC to skip back to where the search started
 * Find next by typing 'n' (for "next")
 * Find previous by typing SHIFT-N or 'p' (for "previous")
 * Search is case sensitive if it contains any UPPER CASE CHARACTERS

m/pagermode-search.go

@@ -10,8 +10,9 @@ import (
 )
 
 type PagerModeSearch struct {
-	pager     *Pager
-	backwards bool
+	pager                 *Pager
+	initialScrollPosition scrollPosition // Pager position before search started
+	backwards             bool
 }
 
 func (m PagerModeSearch) drawFooter(_ string, _ string) {
@@ -101,10 +102,14 @@ func removeLastChar(s string) string {
 
 func (m PagerModeSearch) onKey(key twin.KeyCode) {
 	switch key {
-	case twin.KeyEscape, twin.KeyEnter:
+	case twin.KeyEnter:
 		//nolint:gosimple // The linter's advice is just wrong here
 		m.pager.mode = PagerModeViewing{pager: m.pager}
 
+	case twin.KeyEscape:
+		m.pager.mode = PagerModeViewing{pager: m.pager}
+		m.pager.scrollPosition = m.initialScrollPosition
+
 	case twin.KeyBackspace, twin.KeyDelete:
 		if len(m.pager.searchString) == 0 {
 			return

m/pagermode-viewing.go

@@ -141,13 +141,13 @@ func (m PagerModeViewing) onRune(char rune) {
 		p.handleScrolledDown()
 
 	case '/':
-		p.mode = PagerModeSearch{pager: p, backwards: false}
+		p.mode = PagerModeSearch{pager: p, backwards: false, initialScrollPosition: p.scrollPosition}
 		p.TargetLineNumber = nil
 		p.searchString = ""
 		p.searchPattern = nil
 
 	case '?':
-		p.mode = PagerModeSearch{pager: p, backwards: true}
+		p.mode = PagerModeSearch{pager: p, backwards: true, initialScrollPosition: p.scrollPosition}
 		p.TargetLineNumber = nil
 		p.searchString = ""
 		p.searchPattern = nil