Eeschema: Annotation ignores Numbering Rules

Description

The annotation algorithem in ignores the numbering rules "First free after sheet number X 100 / X 1000". Annotations start always at "1". This applies for schematics with a single page as well as schematics using hierarchical (sub)schematics. The numbering option "Use first free number after: n" works as intended.

Steps to reproduce

1. Open or create an new schematic with at least one component.
2. Open the annotation dialog, select numbering option "First free after sheet number X 100"
3. Click on "Annotate"

KiCad Version

Application: Eeschema

Version: (5.99.0-6535-g66bcfb3ffc), release build

Libraries:
	wxWidgets 3.0.4
	libcurl/7.64.0 OpenSSL/1.1.1d zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3

Platform: Linux 4.19.0-11-amd64 x86_64, 64 bit, Little endian, wxGTK, lightdm-xsession, x11

Build Info:
	Date: Oct 24 2020 18:07:40
	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.67.0
	OCE: 6.9.1
	Curl: 7.64.0
	ngspice: 30
	Compiler: GCC 8.3.0 with C++ ABI 1013

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=OFF
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
	KICAD_SCRIPTING_ACTION_MENU=ON
	BUILD_GITHUB_PLUGIN=ON
	KICAD_USE_OCE=ON
	KICAD_SPICE=ON