release schedule change proposal

[Thomas Monjalon]

For the last 5 years, DPDK was doing 4 releases per year,
in February, May, August and November (the LTS one):
	.02   .05   .08   .11 (LTS)

This schedule has multiple issues:
	- clash with China's Spring Festival
	- too many rushes, impacting maintainers & testers
	- not much buffer, impacting proposal period

I propose to switch to a new schedule with 3 releases per year:
	.03      .07      .11 (LTS)

New LTS branch would start at the same time of the year as before.
There would be one less intermediate release during spring/summer:
.05 and .08 intermediate releases would become a single .07.
I think it has almost no impact for the users.
This change could be done starting next year.

In details, this is how we could extend some milestones:

	ideal schedule so far (in 13 weeks):
		proposal deadline: 4
		rc1 - API freeze: 5
		rc2 - PMD features freeze: 2
		rc3 - app features freeze: 1
		rc4 - last chance to fix: 1
		release: 0

	proposed schedule (in 17 weeks):
		proposal deadline: 4
		rc1 - API freeze: 7
		rc2 - PMD features freeze: 3
		rc3 - app features freeze: 1
		rc4 - more fixes: 1
		rc5 - last chance buffer: 1
		release: 0

Opinions?