http executor: return.code.*.success params were not used in most cases

return.code.*.success params were only used when QNetworkReply error was
NoError, however Qt set a content error code when http status implies an
error (status 500...)
wui: fixed two icons

were using empty/outline/white icons were plain/black icons fit better
switched linux packaging to Qt 5.3.1
config/alerter: cleaner AlerterConfig (re)load process
fixed compilation options for Windows
log: rework to remove bottlenecks and data copy causes

also likely to remove some random crash causes when shuting down
alerter: more robust mail scheduling mechanisms

formerly deciding when to send a mail was purely done through
timers and there were at less a case where a non-monotonic system
clock may disable mail from a queue forever (and by the way create
a memory leak since alerts can accumulate in the queue)

also clarified alerter logs
http executor: log first bytes of http reply when abnormal status

abnormal status being < 200 or > 299
wui: customactions.instanceslist was html-escaped (and shouln't)
ui/params: added %!{min,max}expected{ms,s} task/instances params

and also %!maxbeforeabort[ms,s,ms0,s0} and %!maxexpected{ms,s}0 but it
was too long to write in the header line

this will be convenient for custom action links when drawing statistical
graphs with e.g. graphite
typo fixes
resource consumption model did not take maxinstances into account
wui: avoid word-wrap before or after an icon