ir.model: don't re-create records that were deleted by the user

WARNING: behaviour change on module-updates

See, a few commits ago we introduced the concept of "res_id == 0" for
deleted records. This way we know that the user has explicitly deleted
something.
If a module was updated, it would try to update/create _all_ missing
records, including the deleted. Now, it will just skip these.
rml2txt: remove trailing whitespace, output is a '.txt'

Trivial changes, that is.
rml2txt: fix copyright lines, let it work standalone again

This renderer had heavily been based/influenced by the "rml2pdf" one,
as I had originally implemented it back in 2008.
rml2txt: trivial improvements

This merely improves the coding style.
rml2txt: MAJOR refactoring, use bound boxes, frames, pageGraphics

The previous code had been a quick hack to get this renderer just to
work with plain-flowing-text.
Now, we need to come closer to the actual RML renderer, which shall
calculate widths/heights, word-wrap text and fit flowable stories in
each page frame.
rml2txt: table logic, word-wrap inside cells and respect font size

Instead of the hard-coded 8pt size, now use the document-wide size,
and thus compute table column widths correctly.
Then, wrap text inside those cells and improve table formatting.
rml2txt: remove trailing whitespace
rml2txt: break table rows accross frames

When a table row cannot fit the current frame, break to the next.

Warning: this algo does NOT check if the row can fit the next frame,
it just assumes it fits. This is done _intentionally_, because it
would otherwise trigger the same bug we have with rml2pdf.
rml2txt: fix height calculations, y is at bottom. Leave blank lines

'y' attribute is calculated PostScript-wise, 0 at bottom of paper.
Then, while rendering boxen, we need to leave as many lines as the
difference of current pos and next box "y".

Append a form-feed '\f' at end of each page, so that ext. paginator
can break them exactly.
rml2txt: page limit feature, break if renderer exceeds no. of pages

Same as in rml2pdf, renderer shall stop if in pagination loop.
rml2txt: "pto" and conditional page break tag implementations

PTO is just a block where page break has a custom in-frame prologue.
date_eval: use relativedelta and fix "on 31" date for shorter months

Using relativedelta() we can have "day=31" and still return the last
day of February (28th), say. Our code with `datetime.combine()` did
raise an exception. So, asking for the last day of month would need
a hairy expression (like '... +1month -1day')

The same way, introduce a 'on last' shortcut for the 'on 31' expr,
which makes even more sense.
rml2txt: keep flowable localcontext while rendering its contents

Partially revert the big refactoring commit, that kept localcontext
copy only within this function.
rml2txt: pass drawString contents through process_text()

drawString may have variables to expand, it is more than static text
rml2pdf: implement the 'storyPlace' flowable tag

As in RML User's Guide p.6.4 , storyPlace can render out-of-band
flowables.
In our case, it is trivial for extra frames that need to take part
of our story, but NOT be treated like the main (story) frame. Say,
we need a little "sum" box at the bottom of an invoice, which will
only take the total sum at the end of (invoice) story.
rml2txt: support child flowables: place and storyPlace

These needed a bit of refactoring, so that the _flowable class could
be used outside the main document rendering context.
rml2txt: fix blockTable tag, function name
http_server: double-check that all requests have the same auth.

Badly-configured proxies may break persistence rules
ir_values: avoid borking fields_view_get when reference is "False"

Bad ir.values entries may have "some.model,False" as a reference,
which shall better be ignored.
http_server: quiet re-check for superuser credentials

Previous code would perform a full "authentication", which is also
required to print one log line. This, however, means that remote_logs
would wake up, send the line and trigger a next request, which would
try to authenticate again and again ..

Solution is just not to print the line!