Numeric separator syntax

Sidef allows underscores as a separator character in numeric inputs.

# Int
say 1_2_3;  # 123

# Binary Int
say 0b1_0_1_0_1; # 21

# Hexadecimal Int
say 0xa_bc_d; # 43981

# Rational
say 1_2_3_4.2_5; # 1234.25

# Rational in exponential notation
say 6.0_22e4; # 60220

# Apart from starting the number with an underscore, can be placed anywhere in the number.

say 1234_.25;       # 1234.25
say 1234._25;       # 1234.25
say 1234.25_;       # 1234.25
say 12__34.25;      # 1234.25
# say _1234.25;     # syntax error