Extended Makefile to produce shared libraries on OS X and Linux.
Added shared libraries to .gitignore.
remove duplicated include
Fix incorrect URI/URL unescaping of encoded plusses.
Simplify Makefile.

How I dealt with .d files previously was inspired by GNU make manual
(http://www.gnu.org/software/make/manual/make.html#Automatic-Prerequisites),
but it can be easily simplified to a one line. So here it goes.

+ Note regarding my previous Makefile-related commit:
gperf invocation is purposely using redirection instead of --output-file
option to avoid useless html_unescape.h change when regenerated
(it would add --output-file=html_unescape.h in Command-line: comment).
Unroll MIN as the straight ?: construct

Considering that not all compilers give us MIN implicitly,
and since it's only at one place in the code, losing the MIN
shouldn't be too high a price to pay, readability-wise, for
portability.
Merge pull request #1 from nikai3d/patch-1

Remove duplicated include
Merge pull request #2 from nickbruun/master

Fix incorrect URI/URL unescaping of encoded plusses.
Merge pull request #3 from przemoc/cleaning

Simplify Makefile.
Merge pull request #4 from yanick/min

Unroll MIN as the straight ?: construct
Merge pull request #5 from zacharyvoase/master

Extend Makefile to produce shared libraries
Update readme to add maintanence notice