improve HTTP caching

[bastiK]

JOSM does not properly use HTTP mechanisms for caching, like If-Modified-Since and If-None-Match (etag).

For TMS, there is some code in OsmFileCacheTileLoader, but I think it isn't called as intended.

[bastiK]

In 7242/josm:

add support for If-Modified-Since header in MirroredInputStream (see #10139)

use this for /maps request (sever support has been added) and change update
intervall from 7 days to 1 day

[bastiK]

In 7248/josm:

reworked MirroredInputStream (renamed to CachedFile):

• no more awkwardly open and close InputStream if you just want the underlying file (e.g. to get file inside zip file)
• make it easier to add configuration parameters, without having endless list of parameters for the constructor (Factory style, similar to ImageProvider)

breaks plugins; see #10139

[bastiK]

Fixed plugins in [o30495], [o30496].

[stoecker]

Wha, one of my major improvements renamed. Help. Help...

[bastiK]

The class is gone, but your code​ lives on. :)

[stoecker]

It was one of the few classes created by me, most stuff I did is inside existing classes. At least I found another one which is not only a helper. I wont tell you which or you'll kill it as well :-)

This reminds me how long I care for JOSM and it's fine that it is still actively developed (mainly without me).

[Don-vip]

is there still something to do on this ticket?

[bastiK]

Yes, HTTP caching for TMS requests needs to be investigated and probably improved.

[wiktorn]

HTTP caching for TMS was already improved in April/May.