MySQL fixes/additions/improvements

- fixed GH #187: MySQL: allow access to the underlying connection handle
- added GH #186: MySQL: support for MYSQL_SECURE_AUTH
- fixed GH #174: MySQL: 4GB allocated when reading any largetext or
largeblob field
WinCE fixes for zlib 1.2.8
fix MySQLTest info calls
updated version to 1.5.2
Solaris build
Don't call CloseHandle() twice on Windows (as it causes crashes, or unexpected behavior). This would happen with the following test case:
ProcessHandle handle = Process.launch(...);
handle.kill();
Then as handle gets out of scope, ~ProcessHandle would call CloseHandle() on an already closed handle.
Allow RemoteSyslogChannel to be used again after being closed.
Remove the need for a debug build or debugger when setting POSIX thread names.
Remove the need for a debug build or debugger when setting Win32 thread names.
JSON fixes/refactoring
Foundation/include/Poco/Platform.h: Add support for AArch64.

Add support for big and little endian AArch64 preprocessor defines.
Merge pull request #203 from willnewton/develop

Foundation/include/Poco/Platform.h: Add support for AArch64.
Ability to select the threadpool that will be used to start an Activity.
fixed GH# 173: HTTPClientSession::proxyConnect forces DNS lookup of host names
fixed GH# 194: MessageNotification constructor is inefficient.
fixed GH# 189: Poco::NumberParser::tryParse() documentation bug
fixed GH# 172: IPv6 Host field is stripped of Brackets in HTTPClientSession
fixed GH# 172: IPv6 Host field is stripped of Brackets in HTTPClientSession [testsuite]
xmlparse fix for WinCE
fixed GH# 188: Net: SocketAddress operator < unusable for std::map key