Update CONTRIBUTING.md

Added information about Xephyr and x11trace.
Fixed the crash when toggling fullscreen on empty ws

By checking the client is not null
Fixed crash on toggling fullscreen on empty ws

By checking if the client on the ws is null
or not. Also removed the annoying braces
on a single line if condition.
Merge pull request #12 from neo1691/develop

Fixed the crash when toggling fullscreen on empty ws
Fixes the unused int warning

Just fixes the unused int warning
raised by the compiler.
This commit fixes the unused varible warning

By making a function UNUSED, and passing the variable
to that funtion. The function will just as a dummy stub
and do nothing.

I also tried doing the following
    UNUSED(w);

but this would generate a warning for unused function.
Fixes the unused variable warning

And also makes the code more readable
according to Harvey's liking.
Converted the UNUSED() function into a macro.
Fixed the whitespaces to tabspaces

Also made sure that the tab spaces are set to 8 chars and
not 4 chars.
Merge pull request #13 from neo1691/develop

Fixed compiler warnings about unused variables.
This commit fixes all the remaining warnings

For the discarding const pointer warning,term_cmd was const char *const,
and we were trying to assign that to const char *.
So I changed the const char **cmd to a const char * const * const cmd
Sounds confusing? Declare `cmd` as a const pointer to const pointer to
const char, that's all we did and the warning disappears.

For the other warning, initialization makes integer from pointer without
a cast, initializing the first member of the wss[] array as NULL,
was actually interpreted by the compiler as assigning the first member
of the struct (which happens to be an int) to NULL, and NULL happens
to be a pointer and hence NULL was not compatible with an int.

So changing the NULL value to 0 fixed the warning. I have tested the
binary a little and there seems to be no crashes as of yet.

What I want to know is, you intention behind assigning the first member
of the array wss[] as NULL? Were you trying to make all the members of
the struct Workspace as NULL, or just the first member of ie int layout
as NULL. If you were trying the former, we need to assign all the NULL
eqvivalents of ints and unsigned ints there.

Now I should focus on the clang warnings.
Fixes all the remaining warnings for good as of now.
Merge pull request #15 from neo1691/develop

This commit fixes all the remaining warnings
Resize master only when resizing is visible (i.e. in Stack layouts).
Fixed #9. Zoom and draw_clients were fighting over border sizes.
Fixed log level of debug not showing info events.
Added Comment
Merge pull request #16 from anshulk/develop

Resize master only when resizing is visible (i.e. in Stack layouts).
Removed all warnings caused by unused params.
Some style fixes.