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.

include/remote.h

@@ -52,6 +52,6 @@
 #define CACHE_PATH_FORMAT            "/3ds/"  APP_TITLE  "/cache/%"  JSON_INTEGER_FORMAT
 
 bool themeplaza_browser(EntryMode mode);
-u32 http_get(const char *url, char ** filename, char ** buf, InstallType install_type);
+u32 http_get(const char *url, char ** filename, char ** buf, InstallType install_type, const char *mime_type);
 
 #endif