Closes#4708
This updates jsoncpp, mbedtls, TCLAP and SQLiteCpp to their latest stable release. A few additional changes were needed:
* jsoncpp deprecated Reader, FastWriter and StyledWriter which I've replaced
with some helper functions in JsonUtils.cpp
* SQLiteCpp changed how it builds with external sqlite libraries, now expecting
them to be installed. The simplest path was to remove sqlite from cuberite's
submodule and just use SQLiteCpp's internal version.
e6634ed26c