Fix initialisation of variable 'disp'
Fix a few minor code style issues
Add independent X motion combining 2 prime frequencies

2016-03-27 15:47:01: ERROR[Main]: ServerError: Lua: Runtime error from mod '*builtin*' in callback luaentity_Step(): Node name is not set or is not a string!
2016-03-27 15:47:01: ERROR[Main]: stack traceback:
2016-03-27 15:47:01: ERROR[Main]: 	[C]: in function 'add_node'
2016-03-27 15:47:01: ERROR[Main]: 	/usr/share/minetest/builtin/game/falling.lua:96: in function </usr/share/minetest/builtin/game/falling.lua:43>

Writing an u8 to verbosestream writes a char, not it's numeric value.

This reverts commit 25da0594.

Commit

65c09a96 "Set acceleration only once in falling node"

has made the acceleration being set only once.
But this has introduced a regression.

Fix #3884.

Currently translated at 34.5% (299 of 865 strings)

This is a merger of 2 commits.

Currently translated at 33.7% (292 of 865 strings)

This is a merger of 2 commits.

Currently translated at 93.0% (805 of 865 strings)

This is a merger of 2 commits.

Currently translated at 70.6% (611 of 865 strings)

This is a merger of 2 commits.

Currently translated at 92.4% (800 of 865 strings)

This is a merger of 3 commits.

Currently translated at 34.4% (298 of 865 strings)

This is a merger of 6 commits.

Currently translated at 89.1% (771 of 865 strings)

This is a merger of 2 commits.

Currently translated at 36.6% (317 of 865 strings)

This is a merger of 2 commits.

Currently translated at 51.2% (443 of 865 strings)

This is a merger of 2 commits.

Currently translated at 46.1% (399 of 865 strings)

This is a merger of 3 commits.

Currently translated at 23.2% (201 of 865 strings)

This is a merger of 2 commits.

Currently translated at 47.9% (415 of 865 strings)

Currently translated at 47.9% (415 of 865 strings)

Currently translated at 100.0% (865 of 865 strings)

This is a merger of 2 commits.

Currently translated at 74.9% (648 of 865 strings)

This is a merger of 3 commits.

Currently translated at 54.1% (468 of 865 strings)

Currently translated at 45.3% (392 of 865 strings)

Currently translated at 100.0% (865 of 865 strings)

This is a merger of 3 commits.

Undoubtably this may cause problems later if unchecked.

```
2016-03-22 21:57:52: WARNING[Server]: Assignment to undeclared global "options" inside a function at .../sofar/git/minetest/bin/../builtin/game/chatcommands.lua:862.
```

This allows the player to more easily target and punch connected
nodeboxes, especially if they have a fixed nodebox that is very
small, like technic cabling, or xpanes. Tried it on fences and
my xpane conversion, and happy with the result.

A bool for 'in or under tunnel' was missing
1-node-deep stone ledges were being
replaced with biome surface material

Changes:
  * Fix indentation.
  * Pass strings by const reference.
  * Merge Strfnd and WStrfnd into one class instead of copying them.
  * Remove trailing spaces.
  * Fix variable names.
  * Move to util.
  * Other miscellaneous style fixes.

Exit if cd fails and don't insert '\' in string.

To avoid bright caves at mapchunk borders when generating mapchunks upwards

ABM's are hardcoded to run every 1.0s, NodeTimers are hard coded to
run at every 1.0s. Block mgmt is running every 2.0sec.

However, these timers can be better tuned for both higher and lower
values by server owners. Some server owners want to, and have the
resources to send more packets per second to clients, and so they
may wish to send smaller updates sooner. Right now all ABM's are
coalesced into 1.0 second intervals, resulting in large send queues
to all clients. By reducing the amount of possible timers, one can
get a far better response rate and lower the perception of lag.

On the other side of the camp, some servers may want to increase
these values, which again isn't easily doable.

The global settings abm_interval and nodetimer_interval are set to
current values by default. I've tested with 0.2/0.5 type values
and noticed a greatly improved response and better scattering of
nodetimers, as well as enjoying not faceplanting into doors with
pressure plates anymore.

Before it rendered very badly in HTML.
Also point out what vector.round does.

Before, customisation of DOCDIR did not lead to
changes of the EXAMPLE_CONF_DIR default value.
This was inconsistent with expected behaviour
if you didn't know of the existence of the
EXAMPLE_CONF_DIR variable. The confusion is
very strong, as (for not in place builds) both
DOCDIR and EXAMPLE_CONF_DIR share the same
default value, it is unexpected that setting
CUSTOM_DOCDIR changes the location of all
documentation files but one.

The best meaning of EXAMPLE_CONF_DIR is to
further allow customization of the mt.conf.example
storage place, but otherwise keep defaulting to
whatever DOCDIR is set to, at least for not in
place builds. This patch implements that
behaviour.

Fixes #3863.