Use the exact floating point value, instead of a broken integer
constant. The expression calculating the constant probably relied on
undefined behavior, because it left-shifts a negative value.
This also changes the type of the constant to double, which is perfectly
fine, and maybe better than an integer constant.
Make it more suitable for chaining. This means a function formatting a
value to a string using a static buffer can work exactly like
mp_snprintf_append itself.
Also rename it to mp_snprintf_cat, because that's shorter.
This code is shared between input.conf parser and option parser. Until
now, the performance didn't really matter. But I want to use this code
for JSON parsing too, and since JSON will have to be parsed a lot, it
should probably try to avoid realloc'ing too much.
This commit moves parsing of C-style escaped strings into a common
function, and allows using it in a way realloc can be completely
avoided, if the already allocated buffer is large enough.
I find this annoying. It's the reason common/version.c exists at all.
options.c did this for the user agent, which contains the version
number. Because not including version.h means you can't build the user
agent and use it in mp_default_opts anymore, do something rather awkward
in main.c to initialize the default user agent.
