Do not save in autogen.cfg cvars that have their default values
Disable warnings for transform_u so we can compile with pedantic
Add Cvar::ClearFlags; make it and Cvar::AddFlags return true if the cvar exists.
Implement ‘user archive’ flag for cvars; always save archived variables.

This partially reverts commit 0e8b0ed53a9155134286fca0beff88623f6476b6.

seta now sets USER_ARCHIVE. ARCHIVE is no longer user-settable.
Implement “set -[no-]archive” and “reset [-value]”.
Make /reset accept more than one variable name.
Add /archive and /unarchive for user archiving of cvars.
Minor tidying.
Log: cosmetic change to an argument name of Log::Logger::Logger
Add a generic filter helper for command flags etc.
Update completion code for /set*, /reset, /archive, /unarchive.
Console editing: re-implement ‘swap with next’ and ‘delete to end’.
Textures: implement separate S,T clamping.

This allows you to clamp only the S or T co-ordinate by prefixing the
clamping type keyword with 's' or 't'.

You may specify sNoClamp and tEdgeClamp, for example; but you may not use
both zeroClamp with alphaZeroClamp in the same shader stage since both set
different border colours and only one border colour can be set.
More CompletionItem typedef usage.
Draw a ‘solid’ bbox if cg_drawBBOX > 1.
Change some cvar defaults: r_mode => -2, com_ansiColor => 1
Allow short forms of command switches.
Fix warning removal pragmas in q_shared.h
Don't archive variables marked CVAR_TEMP (Cvar::TEMPORARY).
Merge branch 'master' into for-0.24

Conflicts:
	src/engine/rendererGL/tr_image_dds.cpp