Unify code of power=tower and power=pole

[jragusa]

Fixes #1179

Changes proposed in this pull request:

• Merge layers power-towers and power-poles in project.mml
• Adjust modifications in power.mss

Test rendering with links to the example places:
there is no rendering differences
https://www.openstreetmap.org/#map=17/46.17629/6.23976
z=15

z=16

z=17

[pnorman]

This needs an ORDER BY to get the ordering right.

If you feel comfortable with git, go back one commit and work from there, otherwise don't worry about which order you write things within the WHERE clause.

[pnorman]

This needs an ORDER BY clause to get the correct priority when a pole and tower are nearby.

[jragusa]

I modified the syntax to include ORDER BY condition. Is it correct ?

[kocio-pl]

@jragusa What do plan to do with this code, do you want to make the requested changes?

[jragusa]

yes, I'm working on it.

[imagico]

@jragusa - do you still intend to complete this? The current code does not work because of

openstreetmap-carto/project.mml

Lines 1724 to 1725 in 0000448

	power
	CASE power

Also note if you don't use the prio column anywhere else you don't need it, you can just inline the CASE in the ORDER BY (like done in many of the road queries for example).

[jragusa]

@imagico I have modified according to your remark. What do you think ?

[imagico]

Looks good now.

has been addressed