How do I build lifeograph-2.0.0.rc1 from source?

Hello, I want the latest version but I can't build that version from source.

I am using Linux Ubuntu 20.04 and I have a compilation error.

My actions in the console should be something like:

Step1: meson --buildtype=release --prefix=/usr builddir

Version: 0.53.2
Source dir: /home/ai/Downloads/lifeograph-2.0.0.rc1
Build dir: /home/ai/Downloads/lifeograph-2.0.0.rc1/builddir
Build type: native build
Project name: net.sourceforge.Lifeograph
Project version: 2.0.0
C++ compiler for the host machine: c++ (gcc 9.3.0 "c++ (Ubuntu 9.3.0-10ubuntu2) 9.3.0")
C++ linker for the host machine: c++ ld.bfd 2.34
Host machine cpu family: x86_64
Host machine cpu: x86_64
Found pkg-config: /usr/bin/pkg-config (0.29.1)
Run-time dependency gtkmm-3.0 found: YES 3.24.2
Run-time dependency enchant-2 found: YES 2.2.8
Run-time dependency champlain-gtk-0.12 found: YES 0.12.20
Run-time dependency libgcrypt found: YES 1.8.5
Run-time dependency threads found: YES
Configuring config.h using configuration
Program meson_post_install.py found: YES (/usr/bin/python3 /home/ai/Downloads/lifeograph-2.0.0.rc1/meson_post_install.py)
Build targets in project: 7

Found ninja-1.10.0 at /usr/bin/ninja

Step2: cd builddir; ninja

FAILED: lifeograph@exe/src_diarydata.cpp.o
c++ -Ilifeograph@exe -I. -I.. -I../ -I/usr/local/include/gtkmm-3.0 -I/usr/local/lib/gtkmm-3.0/include -I/usr/local/include/gdkmm-3.0 -I/usr/local/lib/gdkmm-3.0/include -I/usr/include/atkmm-1.6 -I/usr/include/gtk-3.0/unix-print -I/usr/include/giomm-2.4 -I/usr/lib/x86_64-linux-gnu/giomm-2.4/include -I/usr/include/pangomm-1.4 -I/usr/lib/x86_64-linux-gnu/pangomm-1.4/include -I/usr/include/glibmm-2.4 -I/usr/lib/x86_64-linux-gnu/glibmm-2.4/include -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/gtk-3.0 -I/usr/include/gio-unix-2.0 -I/usr/include/pango-1.0 -I/usr/include/fribidi -I/usr/include/harfbuzz -I/usr/include/atk-1.0 -I/usr/include/cairomm-1.0 -I/usr/lib/x86_64-linux-gnu/cairomm-1.0/include -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/uuid -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/sigc++-2.0 -I/usr/lib/x86_64-linux-gnu/sigc++-2.0/include -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/local/include/enchant-2 -I/usr/include/clutter-gtk-1.0 -I/usr/include/champlain-0.12 -I/usr/include/libsoup-2.4 -I/usr/include/libxml2 -I/usr/include/clutter-1.0 -I/usr/include/cogl -I/usr/include/libdrm -I/usr/include/json-glib-1.0 -fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wnon-virtual-dtor -std=c++14 -O3 -DGETTEXT_PACKAGE=net.sourceforge.Lifeograph -DHAVE_CONFIG_H -pthread -MD -MQ 'lifeograph@exe/src_diarydata.cpp.o' -MF 'lifeograph@exe/src_diarydata.cpp.o.d' -o 'lifeograph@exe/src_diarydata.cpp.o' -c ../src/diarydata.cpp
../src/diarydata.cpp:243:18: error: stray ‘\317’ in program
  243 | const double ��1{ p1.latitude * to_rad }; // in radians
      | ^
../src/diarydata.cpp:243:19: error: stray ‘\206’ in program
  243 | const double ��1{ p1.latitude * to_rad }; // in radians
      | ^
../src/diarydata.cpp:244:18: error: stray ‘\317’ in program
  244 | const double ��2{ p2.latitude * to_rad }; // in radians
      | ^
../src/diarydata.cpp:244:19: error: stray ‘\206’ in program
  244 | const double ��2{ p2.latitude * to_rad }; // in radians
      | ^

....