Feature: update conan new to latest guidelines

[SSE4]

update several minor things in conan new command:

• add fPIC option handling
• add homepage attribute
• add header_only to package_id
• update to cmake_minimum_required(VERSION 3.1)

this makes it easier to create package skeletons - fewer things need to be edited

Changelog: Feature: Update conan new to latest guidelines.
Docs: omit

#tags: slow

[n-bes]

Could you update test_cmake template? By default it is not allowed by hook KB-H048:

[HOOK - conan-center.py] pre_export(): ERROR: [CMAKE VERSION REQUIRED (KB-H048)] The test_package/CMakeLists.txt requires CMake 3.1 at least. Update to 'cmake_minimum_required(VERSION 3.1)'. (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H048)

[SSE4]

Could you update test_cmake template? By default it is not allowed by hook KB-H048:

[HOOK - conan-center.py] pre_export(): ERROR: [CMAKE VERSION REQUIRED (KB-H048)] The test_package/CMakeLists.txt requires CMake 3.1 at least. Update to 'cmake_minimum_required(VERSION 3.1)'. (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H048)

np, updated

[SSE4]

/cc @ericLemanissier @Croydon @madebr @uilianries @SpaceIm @prince-chrismc
lemme know if there is something else useful to update in that shot

[prince-chrismc]

A few suggestions because of comments that are common

[prince-chrismc]

I am fairly certain this is also expected during review

Suggested change

	def config_options(self):
	if self.settings.os == "Windows":
	del self.options.fPIC
	def config_options(self):
	if self.settings.os == "Windows":
	del self.options.fPIC
	def configure(self):
	if self.options.shared:
	del self.options.fPIC

[memsharded]

Not completely sure, many recipes do not implement it yet. I would say wait until this is discussed a bit more, seems that some Conan built-in helpers would be better.

[SSE4]

agree

    def config_options(self):
        if self.settings.os == "Windows":
            del self.options.fPIC

this code has 361 occurrences on CCI

    def configure(self):
        if self.options.shared:
            del self.options.fPIC

this one is only 264.
so, probably, it might be too early to enforce that, as it's not an established practice on CCI.
earlier we also had proposal for so called shared_library_package_id to be used in recipes, I don't remember what was a conclusion.
we need to talk about these two IMO before we start to recommend them.

[danimtb]

I understand this is more explicit than just a recipe without settings, but we are adding more code here that is unneeded. If this is a pattern followed in CCI for example, then I am ok with it. Maybe we should consider it for conan 2.0 (enforce settings always?)

[SSE4]

I guess it might be error prone without explicit, e.g. if you add some settings and options to the recipe after running conan new, it's easy to forget about this method.
same if you decide to add more requirements, as header_only now contains:

self.requires.clear()

I believe the same package id is expected to be generated regardless of requires, which is not the case in the current template.

[jgsogo]

LGTM