Created new share icon; Now tapping on a file brings app in single file selection mode (TODO: add visual feedback of this single selection state); Long pressing still shows multi select; Added switch statements for the remaining icons in the UI; created the function that would soon handle the visibility of the icons in the action bar.
Merge pull request #51 from AlexKolpa/UI_Icons

Looks good @OlivierHokke, thanks and sorry for the delay. Merging.