While Keyman Core already supported the base layout flags, they were not
being passed in from Keyman Engine for Windows. This meant that any
rules that used `baselayout` would fail, such as in sil_ipa with AltGr+0
for }
0bf72bed74/release/sil/sil_ipa/source/sil_ipa.kmn (L348-L350)
This patch adds support for the following properties:
* KM_KBP_KMX_ENV_BASELAYOUT: the legacy base layout name, e.g. kbdus.dll
* KM_KBP_KMX_ENV_BASELAYOUTALT: the BCP 47 base layout name, e.g. en-US
* KM_KBP_KMX_ENV_SIMULATEALTGR: whether the user has selected to emulate
AltGr with Ctrl+Alt, for example on laptops without a right alt key.
* KM_KBP_KMX_ENV_BASELAYOUTGIVESCTRLRALTFORRALT: whether the system base
layout in use generates Ctrl+RAlt when RAlt is pressed, which can be
true for many European system layouts. This is necessary when
associating the keyboard with a European language because the base
keyboard becomes the language's default keyboard, rather than kbdus.
0d4a6e428a