Fix: issue #4 and #5 (#6)

- Issue #4: currently there is no official release yet so we cant
download from installer
- I added an installer debugger here to test
(f091dbf13bdf109b631951e2558651f560ca8b84)
- Issue #5: my another library
[fuzzy](https://github.com/versenilvis/fuzzy/) has a logic bug so it
causes crash, fix d479c6cb4d8453e50366c9839daaabb45a98a2df

- Other:
  -  remove unneeded comments (edd9d05fdd16e682b6b416913e2fa9c3f6599956)
  - Add some tests
  - Fix reload crash (3a76e78e655fd8daafb635ec0937667325f75ee4)
- New optimized build command (56a4a815f836271b861f32795d2df3b25a3dffc0)

commands/core/system.go

@@ -3,13 +3,19 @@ package core
 import (
 	"os"
 	"path/filepath"
+	"sync"
 )
 
-var pathCmds = make(map[string]bool)
+var (
+	pathCmds     = make(map[string]bool)
+	pathCmdsOnce sync.Once
+)
 
 // scanExternalCommands populates pathCmds with system executables
 func scanExternalCommands() {
-	scanPath()
+	pathCmdsOnce.Do(func() {
+		scanPath()
+	})
 }
 
 // scanPath populates pathCmds with all executable files found in path environment variable