Networking rework (#240)

* Began refactoring http_get. Still a few cases to handle, but it works.

* Introduced error enum; handle error 406; handle a misbehaving server; redirect_url leaked memory (L888)

* Allowed calls to http_get to pass NULL as acceptable_mime_types

* Removed status_code from header struct; eventually planning to move most of parse_header's logic back to http_get, so this makes sense

* Moved some more logic back into http_get
Note: currently behaves weirdly with some QR codes, including but probably not limited to ones pointing to TinyURL.

* Handle redirects correctly; other rearrangements

* Formatting

* Handle HTTP 303 See Other correctly

* Removed "Download failed" error in camera.c due to all related failures being handled in http_get

* Fixed missing loading bar; started working on unchunked download

* Added unchunked download

* Reintroduced the download progress bar, rolled back to always doing chunked download

* URL length caps at 2083 chars

* Slightly more efficient

* Correctly handle incorrect filesize header
TODO: reorder clauses to remove the goto?

* Fixed illegal characters, removed unnecessary logic (technically a regression, as we always have to realloc now)

* Finally finished up status code handling. Fixed a memory leak when the server fails conneg.

source/camera.c

@@ -229,7 +229,7 @@ void update_qr(qr_data *data)
             draw_install(INSTALL_DOWNLOAD);
             char * zip_buf = NULL;
             char * filename = NULL;
-            u32 zip_size = http_get((char*)scan_data.payload, &filename, &zip_buf, INSTALL_DOWNLOAD);
+            u32 zip_size = http_get((char*)scan_data.payload, &filename, &zip_buf, INSTALL_DOWNLOAD, "application/zip");
 
             if(zip_size != 0)
             {
@@ -288,19 +288,17 @@ void update_qr(qr_data *data)
                     }
                     else
                     {
+                        // TODO: handle more elegantly
                         throw_error("Zip downloaded is neither\na splash nor a theme.", ERROR_LEVEL_WARNING);
                     }
                 }
                 else
                 {
+                    // TODO: marked for deletion
                     throw_error("File downloaded isn't a zip.", ERROR_LEVEL_WARNING);
                 }
                 free(zip_buf);
             }
-            else
-            {
-                throw_error("Download failed.", ERROR_LEVEL_WARNING);
-            }
 
             free(filename);
         }