String buffer API
-----------------

First off, the major design choices. the most important thing to keep in mind
when using the API is that it is designed for low-level usage, The basic error checking
is removed (like checking if the input strbuf pointer is null). +
This is not done to gain speed, but because this is a buffer API, you should in almost every case allocate
the structure on the stack or have it passed from a function that has it allocated on the stack. +
Other types of skipped error checking is for example if the ->len member is in range of
the allocated block. (obviously this is checked in functions that may need to expand the memory)

Data structures
~~~~~~~~~~~~~~~

* `strbuf_t`

The ->buf member is yours to mess with if you want, but you should never go beyond ->len. +
A `NULL` terminating character is located at ->len+1 at all times so it is safe to use the ->buf member
on any function that relies on the input being a valid C string. The API will never rely on this
and it's possible to have embedded `NULL`'s because of that.

NOTE: ->alloc_size and ->len should *not* be messed with, only `strbuf_*` functions will know how to handle those properly.

Functions
~~~~~~~~~

`strbuf_setlen()`::

    Sets the length of the buffer. +
    This function will not allocate memory, it only sets ->len and
    assure that the string is null-terminated at the new position.

`strbuf_avail()`::

    Returns the number of characters that are allocated but not used in the buffer.

`strbuf_append()`::

    This function will append the buffer with the contents of 'ptr'
    and will always copy exactly 'len' bytes. (if memory can be obtained ofcourse)

`strbuf_appendf()`::

    Adds the formated-string 'fmt' to the end of ->buf.

`strbuf_append_va()`::

    Adds the formated-string 'fmt' (generated by a `va_list`) to the end of ->buf. +
    Returns the number of characters that should have been written if ->buf was large enough. +
    Therefor if the function returns zero. all characters has been written. +
    +
    Example usage:
+
----
va_start(va, fmt);
len = strbuf_append_va(s, fmt, va);
va_end(va);

if (len > 0) {
    strbuf_expand(s, len);
    va_start(va, fmt);
    len = strbuf_append_va(s, fmt, va);
    va_end(va);
}
----
`strbuf_append_str()`::

    Will add the 'str' C-string to the end of ->buf

`strbuf_append_ch()`::

    Adds one character 'ch' to the end of ->buf

`strbuf_append_repeat()`::

    Adds 'len' characters of 'ch' to the end of ->buf

`strbuf_reduce()`::

Will reduce ->buf by 'len' bytes from the end.
+
NOTE: This doesn't shrink the memory block
    just changes the size and properly `NULL` terminates the now reduced space.

`strbuf_trim()`::
`strbuf_rtrim()`::
`strbuf_ltrim()`::

    Removes space characters from the beginning (ltrim) of the ->buf string, the end (rtrim) or both (trim).

`strbuf_rchop()`::

    Chops off everything to the right of the rightmost 'ch' encountered in the string.

`strbuf_rev()`::

    Reverses the ->buf string.

`strbuf_squeeze()`::

    Squeezes "together" sequences of 'ch' into one character.

`strbuf_term()`::

    ensure that ->buf is terminated with 'ch'. Will not change ->buf if it is already terminated.

`strbuf_explode()`::

Returns a NULL terminated list of string buffers, each containing a substring of 'str' splitted by delimiter'. +
Returns `NULL` if 'delimiter' does not exists in 'str'.
+
TIP: use `strbuf_free_list()` to free the entire list.
+
NOTE: 'delimiter' is not included in the list.

`strbuf_release()`::

    This function should be used to detach the ->buf member from the `strbuf_t` structure. +
    A `malloc()`'ed C string of size `strlen()+1` is returned that you are now responsible for.

`strbuf_free()`::

    Free's all the memory (allocated on the heap) associted with the `strbuf_t` structure.

`strbuf_free_list()`::

    Free's all the memory from an NULL terminated list of string buffers.