Handling file opening (#329)

* Add function to escape a shell argument.

* Keep track of the last used window.

* Implement support for the open-file event.

* The shell escape regex needs parentheses to be captured.

* Removed lastWindow and added getLastFocusedWindow method to app

* Create window create new session only if no callback passed

* Added app.windowCallback to handle open-file before "ready"

* Small lint fixes

* Differeent open file handling: check if it is directory, and if the file is executale or not

* Small fixed and added some comments

* Added php-escape-shell module in place of custom escapeShellArgument()

* Fixed wrong code and added detailed comment

* Aliased php_escapeshellcmd import

* Rebased; added error handling in OpenFile

* changed string contatenation with template literal

* Pinned php-escape-shell dependency

* Typo fix

* getLastdFocusedWindow now uses Array.prototype.reduce()

* Notify users of unexisting path while open file

lib/utils/file.js

@@ -0,0 +1,17 @@
+// Based on https://github.com/kevva/executable
+// Since this module doesn't expose the function to check stat mode only,
+// his logic is pasted here.
+// Opened an issue and a pull request about it,
+// to maybe switch to module in the future:
+// Issue: https://github.com/kevva/executable/issues/9
+// PR: https://github.com/kevva/executable/pull/10
+
+export function isExecutable (fileStat) {
+  if (process.platform === 'win32') return true;
+
+  return Boolean(
+    (fileStat['mode'] & parseInt('0001', 8)) ||
+    (fileStat['mode'] & parseInt('0010', 8)) ||
+    (fileStat['mode'] & parseInt('0100', 8))
+  );
+}