Eliminated ref_t. Some more convention fixes

[ethouris]

Fixes #943, #945

The new convention for passing parameters by writable reference applied. The use of ref_t and Ref has been eliminated, as well as the definitions thereof.

The new convention is:

1. Reference parameters must have w_ prefix and pointer parameters - pw_ prefix.
2. Passing any expression that resolves to a reference to a writable object requires (extra_parentheses) around the whole expression. This applies to:
   • passing single variable to a function
   • passing a field of a structure
   • passing a pointer to a writable object, both as pointer or as reference
   • assigning a pointer to a pointer-type field of another structure to be later passed to a function for writing
   • regardless if this reference variable is a local variable, or a parameter pass-through

The above rules don't embrace passing a non-writable object, usually preferred as const, but also when it's required to be passed by writable pointer or reference, but the function doesn't modify it.

Also the order of parameters is changed to the convention - writable reference parameters should be placed after value parameters.

[maxsharabayko]

Looks like it also depends on PR #1028. At least I see some function from that not yet merged PR in this one.

[ethouris]

Purged of any premature merges. Now the PR is completely independent.

[maxsharabayko]

This looks like something from another PR.

[maxsharabayko]

Looks good.
Ideally, this is better to be divided into two commits: one for changes to core, another for changes to the apps.
This can be easily done with two git commands:

git reset @~3
git add ./srtcore/*
git commit -m "[core] Eliminated ref_t from the core"
git add ./apps/*
git add ./testing/*
git commit -m "[apps] Eliminated ref_t from apps"
git push --force

[ethouris]

I understand, but the trouble is that splitting makes sense if they can be independent - whereas as this involves deletion of ref_t and Ref, this change applies to both, or at least one would be dependent on the other and require a blocking merge cycle.

[maxsharabayko]

Well, it is simple to solve. The first commit should remove ref_t from apps, the second - from the core.

[maxsharabayko]

So like this then

git reset @~3
git add ./apps/*
git add ./testing/*
git commit -m "[apps] Eliminated ref_t from apps"
git add ./srtcore/*
git commit -m "[core] Eliminated ref_t from the core"
git push --force

[rndi]

I must say these new prefixes do look silly. Also, experience tells me they are going to be hard to enforce or maintain. But no (serious) harm done and this is definitely better than 'Ref()' usage.

Other than that, please resolve the merge conflict with the master branch. Thanks!