regression: dropping files on the window

Dependencies

• [2] 5STHSG4U remove some duplication
• [*] CE4LZV4T drop last couple of manual tests
• [*] UHB4GARJ left/right margin -> left/right coordinates
• [*] BPWFKBXT new test: dragging and dropping a file on lines.love
• [*] LF7BWEG4 group all editor globals
• [*] YT5P6TO6 bugfix: save previous file when dropping a new one on
• [*] OTIBCAUJ love2d scaffold
• [*] 5T2E3PDV couple of bugfixes to file-handling

Change contents

• edit in main_tests.lua at line 22
  [5.17201]

  [6.117]
  + Editor_state = edit.initialize_test_state()
• edit in main_tests.lua at line 45
  [7.85118]

  [8.7]
  + edit.draw(Editor_state)
• edit in main.lua at line 130
  [10.16]

  [2.179]
  + Text.redraw_all(Editor_state)