Update OurCS2.xtext

tentativa de inserir operacoes aritmeticas (comentado), inserido declaracao de variaveis, constantes e campos (field)

estado: antes de merge com REAL_LITERAL e PP_DIRECTIVE

log de warnings obtido:

warning(200): ../org.xtext.example.ourcs2/src-gen/org/xtext/example/mydsl1/parser/antlr/internal/InternalOurCS2.g:1798:1: Decision can match input such as "'bool' RULE_ID '=' 'false'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../org.xtext.example.ourcs2/src-gen/org/xtext/example/mydsl1/parser/antlr/internal/InternalOurCS2.g:1798:1: Decision can match input such as "'bool' RULE_ID '=' 'null'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../org.xtext.example.ourcs2/src-gen/org/xtext/example/mydsl1/parser/antlr/internal/InternalOurCS2.g:1798:1: Decision can match input such as "'bool' RULE_ID '=' RULE_STRING" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../org.xtext.example.ourcs2/src-gen/org/xtext/example/mydsl1/parser/antlr/internal/InternalOurCS2.g:1798:1: Decision can match input such as "'bool' RULE_ID '=' 'true'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../org.xtext.example.ourcs2/src-gen/org/xtext/example/mydsl1/parser/antlr/internal/InternalOurCS2.g:1798:1: Decision can match input such as "'bool' RULE_ID '=' RULE_INT" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input