Merge pull request #189 from stachenov/feature/cibadge

Add CI badge, fix conan badge link, add basic build instructions.

.gitignore

@@ -4,3 +4,5 @@
 *.tags
 *.user
 *.swp
+.idea/
+cmake-*

README.md

@@ -1,9 +1,10 @@
 # Quazip
 
-[![Conan Center](https://shields.io/conan/v/quazip)](https://conan.io/center/quazip)
+[![CI](https://github.com/stachenov/quazip/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/stachenov/quazip/actions/workflows/ci.yml)
+[![Conan Center](https://shields.io/conan/v/quazip)](https://conan.io/center/recipes/quazip)
 
 QuaZip is the C++ wrapper for Gilles Vollant's ZIP/UNZIP package
-(AKA Minizip) using Trolltech's Qt library.
+(AKA Minizip) using Qt library.
 
 If you need to write files to a ZIP archive or read files from one
 using QIODevice API, QuaZip is exactly the kind of tool you need.
@@ -24,3 +25,36 @@ Distributed under LGPL, full details in the COPYING file.
 
 Original ZIP package is copyrighted by Gilles Vollant, see
 quazip/(un)zip.h files for details, but basically it's the zlib license.
+
+## Build
+
+You need at least the following dependencies:
+- zlib
+- Qt6, Qt5 or Qt4 (searched in that order)
+
+If you built Qt from source and installed it, you might need to tell CMake where to find it, for example: `-DCMAKE_PREFIX_PATH="/usr/local/Qt-6.6.2"`.  
+Alternatively, if you did not install the source build it might look something like: `-DCMAKE_PREFIX_PATH="/home/you/qt-everywhere-src-6.6.2/qtbase/lib/cmake"`.  
+Replace `qtbase` if you used a custom prefix at `configure` step.
+
+Qt installed through Linux distribution packages or official Qt online installer should be detected automatically.
+
+CMake is used to configure and build the project.
+
+```
+cmake -B build
+cmake --build build --config Release
+sudo cmake --install build
+cmake --build build --target clean
+```
+
+CMake options
+
+| Option                   | Description                                                                                           | Default |
+|--------------------------|-------------------------------------------------------------------------------------------------------|--------------|
+| `BUILD_SHARED_LIBS`      | Build QuaZip as a shared library                                                                      | `ON`         |
+| `QUAZIP_INSTALL`         | Enable installation                                                                                   | `ON`         |
+| `QUAZIP_USE_QT_ZLIB`     | Use Qt's bundled zlib instead of system zlib (**not recommended**). Qt must be built with `-qt-zlib`. | `OFF`        |
+| `QUAZIP_ENABLE_TESTS`    | Build QuaZip tests                                                                                    | `OFF`        |
+| `QUAZIP_BZIP2`           | Enable BZIP2 compression                                                                              | `ON`         |
+| `QUAZIP_BZIP2_STDIO`     | Output BZIP2 errors to stdio when BZIP2 compression is enabled                                        | `ON`         |
+