This reverts commit 889de46f.

 Fixes ArcticaProject/nx-libs#775.

nxagent: Also provide auto DPI feature via nx/nx option 'autodpi', taking only effect on session startups.

Fixes ArcticaProject/nx-libs#617.

nxcomp/src/Loop.cpp: Make know the agent option 'keyconv' to nxcomp and tolerate it as a valid option.

Fixes ArcticaProject/nx-libs#630.

Fixes ArcticaProject/nx-libs#657.

with very few exceptions which require careful thinking ;-)

==28424== 6 bytes in 1 blocks are definitely lost in loss record 1 of 7
==28424==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==28424==    by 0x541D4D9: strndup (strndup.c:43)
==28424==    by 0x4E8AD4B: ChannelEndPoint::getTCPHostAndPort(char**, long*) const (ChannelEndPoint.cpp:311)
==28424==    by 0x4EBE9CC: ConnectToRemote(ChannelEndPoint&) (Loop.cpp:6656)
==28424==    by 0x4EB0A4C: SetupProxyConnection() (Loop.cpp:3205)
==28424==    by 0x4EDC81A: handleNegotiationInLoop(int&, fd_set&, fd_set&, timeval&) (Loop.cpp:14308)
==28424==    by 0x4EAE40F: NXTransPrepare (Loop.cpp:2576)
==28424==    by 0x4EAA801: NXTransContinue (Loop.cpp:1610)
==28424==    by 0x4EB50C9: WaitCleanup() (Loop.cpp:4436)
==28424==    by 0x4EA9507: NXTransProxy (Loop.cpp:1235)
==28424==    by 0x400B2A: main (Main.c:111)

==7689== 50 bytes in 5 blocks are definitely lost in loss record 1 of 2
==7689==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7689==    by 0x54074D9: strndup (strndup.c:43)
==7689==    by 0x4E7D803: ChannelEndPoint::getTCPHostAndPort(char**, long*) const (ChannelEndPoint.cpp:309)
==7689==    by 0x4EC9D93: ConnectToRemote(ChannelEndPoint&) [clone .constprop.144] (Loop.cpp:6660)
==7689==    by 0x4ECB94E: SetupProxyConnection() (Loop.cpp:3204)
==7689==    by 0x4ECE824: handleNegotiationInLoop(int&, fd_set&, fd_set&, timeval&) [clone .isra.129] (Loop.cpp:14312)
==7689==    by 0x4ED0F8A: NXTransPrepare (Loop.cpp:2575)
==7689==    by 0x4ED1C35: NXTransContinue (Loop.cpp:1609)
==7689==    by 0x4ED1D7B: WaitCleanup() (Loop.cpp:4440)
==7689==    by 0x4ED2343: NXTransProxy (Loop.cpp:1234)
==7689==    by 0x400B2A: main (Main.c:111)

(partially) fixes ArcticaProject/nx-libs#612

(partially) fixes ArcticaProject/nx-libs#612

Fix another memleak

(partially) fixes ArcticaProject/nx-libs#612

was missing in the non-abstract code path

(partially) fixes ArcticaProject/nx-libs#612

fixes a memory leak

(partially) fixes ArcticaProject/nx-libs#612

Especially don't flush data out mid-append.
Doing so will lead to the next append operation failing.

Should fix messages queuing up indefinitely (until they are discarded at
program termination, at least) and missing messages in general.

Fixes: ArcticaProject/nx-libs#577
Fixes: ArcticaProject/nx-libs#611

Fixes this:

CXX      Loop.lo
Loop.cpp: In function 'void handleCheckResultInLoop(int&, int&, int&, fd_set&, fd_set&, timeval&, timeval&)':
Loop.cpp:14080:68: warning: declaration of 'startTs' shadows a global declaration [-Wshadow]
                                             struct timeval &startTs)
                                                                    ^
Loop.cpp:1020:13: note: shadowed declaration is here
T_timestamp startTs;

Fixes ArcticaProject/nx-libs#545

Should be used instead of free() calls and will clear the pointer after
calling free(). This can prevent double-free or use-after-free errors.

Some functions' return values are never used anywhere, so drop them.

This corrects a flaw that stayed undetected for 2.5 years, introduced via
c5a2cf82

Fixes ArcticaProject/nx-libs#573

Fixes: ArcticaProject/nx-libs#536

Allowing overrides via NX_TEMP and TEMP breaks system using
pam_tmpdir.so and most server infrastructure expects the location to be
fixed anyway.

Regression fix for f855b3b6. Caused FTBFS with Loop.cpp:2669:0: error: unterminated #ifdef (#ifdef TIME).