Due to compatibility concerns, this is temporarily disabled.

  * The time command now accepts parameters in the form <hour>:<minute>,
    and if invoked with no parameters returns the current time in said format.

Also rename method to better match what it does.

This enables srp.

Before this commit autofast for Android was ignored if the user was sneaking, digging or building. There is no reason for this and it impedes movement control

Android terminated immediately after start since commit
181f7baa
because library wasn't loaded, and libminetest.so required
libgmp.so.10 instead of libgmp.so.

The second issue has been solved by the linker flags.

Items dropped into unloaded map space will crash game so here's a fix...

Don't ident too much, and add a comment.

Also optimize json's library

Adds everything needed for SRP (and everything works too),
but still deactivated, as protocol v25 init packets aren't final yet.
Can be activated by changing the LATEST_PROTOCOL_VERSION header to 25
inside networkprotocol.h.

Uses system provided libgmp if found, if not it falls back to mini-gmp.

On Debian 8...
```
Package libjpeg8-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  libjpeg62-turbo-dev
```
Using libjpeg-dev should make the OS select the most appropriate lib to be installed.
These are the packages available on Debian 8.
```
libjpeg-dev - Development files for the JPEG library [dummy package]
libjpeg-turbo-progs - Programs for manipulating JPEG files
libjpeg-turbo-progs-dbg - Programs for manipulating JPEG files (debugging symbols)
libjpeg62-turbo - libjpeg-turbo JPEG runtime library
libjpeg62-turbo-dbg - Debugging symbols for the libjpeg-turbo JPEG library
libjpeg62-turbo-dev - Development files for the libjpeg-turbo JPEG library
libturbojpeg1 - TurboJPEG runtime library - SIMD optimized
libturbojpeg1-dbg - TurboJPEG runtime library - SIMD optimized (debugging symbols)
libturbojpeg1-dev - Development files for the TurboJPEG library

```
This seems to work on all current Debian versions, Wheezy, Jessie and Sid.
https://packages.debian.org/wheezy/libjpeg-dev
https://packages.debian.org/jessie/libjpeg-dev
https://packages.debian.org/stretch/libjpeg-dev

Im not sure if Ubuntu has this dummy package.

http://packages.ubuntu.com/search?keywords=libjpeg-dev

Perhaps this should be further discussed.

libjpeg8-dev -> libjpeg-dev

Now matches function comment

Improve schematic file-saving interface
Add ability to create temporary test files

Fixes #2678

This simplifies NodeResolver logic and makes some interfaces cleaner.